I wish that I knew what I know now...

1) You will be back if you want to return. Don't do it all on this trip.
2) Small rural areas are interesting in different ways than are cities.
3) Every disaster is a good story later, although avoiding those which cost a lot of money are good.
4) Don't do U-turns in Vienna.

1) Eat local, drink local.

2) Put the guidebook down and explore. Don't plan every minute of your trip. Be open to new experiences.

3) Do and see the things you want and skip those you don't. Even if the guidebook, travel expert, guru or friend thinks you should. It's your money and your time.

4) Always pack Pepto Bismol. It may not be available where you need it.

5) If you like a place and want to return, do so. If you have no desire to go somewhere, don't. ( see #3)

6) Don't listen to the fear mongering about foreign travel from people who don't travel internationally.

@OP: You have a nice way of expressing yourself.
I guess many of us feel the way you do (I know I do), but no use sweating it--because I guess no one ever knows back then what they know now. Sometimes I think I don't even know now some of what I knew back then.

Smiles go a long way towards ensuring trip enjoyment. Everything seemed so much more serious back then when I wasn't so comfortable getting out of my comfort zone! But the most important thing I know now that I wish I had known then was that I really needed to "slow down and smell the roses.....", Europe and the rest of the world wasn't going away any time soon. I do slow things down now in my travels and love my 10 day (at least) stays in large European cities ( I'm guessing because I live in the country?) as well as the point-to-point trips I take. Life is a lifelong learning journey.

Admittedly, I made mistakes in traveling especially in the 3 trips in the 1970s, nothing crucial but still stupid errors when judging a situation. True, I had energy to waste and was a bit spoiled, I insisted on staying in a hostel or at most a small hotel/Pension.

"...what would you tell your younger better-looking self?" Good question. Be more adventurous, be less conservative in your traveling, get out of the solo comfort zone. There are certain places in Germany I should have gone to (looking back) in the early 1970s...Frankfurt, Hameln, Celle to list those most important.

In 1995 learned the hard way that driving distances in England are deceiving and it's better not to try to do too much in one day. On a bank holiday weekend with alot of traffic, 2 friends and I drove from Oxford to Wells to Salisbury to Stonehenge back to Oxford. By the end of the day, we were tired and irritable, and hadn't enjoyed what we rushed to see.

"Better not to try to do too much in one day."
Words of wisdom.
It just might be that some of Rick's guidebooks tend to get you a bit in trouble with this one.
I realize most Americans don't get 6 weeks paid vacation like some EU citizens, but still...why use guidebooks to encourage us to do more than can be enjoyed? (I know, Rick doesn't read the Forum...but if he did....)

Good points. If you're disinterested in a must-see attraction, then forget it. I like museums but when they're super crowded it's not very enjoyable.

"...what would you tell your younger better-looking self?"

Wear sunscreen. But really, it would be that you will enjoy travel more if you don't try to pinch every penny.

If I had a "life do-over":
I would be less dedicated to my job and would take more vacation time to travel to more places early in life.

I would choose a different major in college and choose one that included a study abroad program.

Advice to others....Frank II has a terrific list. I would just add to that:
Don't travel with grumpy or negative friends.
Travel with friends who are friendly, open minded and smile a lot.

Do your own research on historical sights that have meaning for you.
You can see some great things in churches, cathedrals and towns that are off the beaten tourist paths.

Make the most of what you see and what you do. Even write it up each day: re-reading those accounts may be the only way your older self can re-visit that place and that time.
However much you intend to, you may never go back there, and - if you do - it may have changed so much that you are glad you still have those memories of when it was little visited and unknown.

• Keep a good log or journal so you can reference it for memories, repeats, or to help friends and people on the RS Forum
• Don’t be afraid to change your plans on the fly
• Pack lighter than you think possible
• Make your trips as long as possible. 2 week’s is always better than 10 days, but 3 weeks are even better.
• Stay longer in fewer places
• Don’t go somewhere because you think you should
• Private tours are a worthy splurge. Drink cheap wine, cook dinner, picnic, but pay for a private tour where it counts,

I like Bob Seger's reversal, in one of his earlier songs: Wish I didn't know now what I didn't know then.

Wear more sunscreen - yes!
Choose study abroad, not the boyfriend (although we had many great adventures)
Dont skimp - yes! (pay for the train ticket, dont try to avoid the conductor, get busted, and use up one punch on your eurail pass)

But still do
travel on a whim, trust your gut (still dont accept the invitations to the guys' houses even though they seem perfectly nice and its a free place to stay), regret things you've done, not those you haven't

If your impulse is to pull over and have a better look at something- do it!

Schedule time to go for a walk in a nearby park and feed the ducks.

Love that song. . .

1) pack lighter. He who has the most stuff is sweaty, not the winner
2) we took our kids out of school for a few days here and there to make a school break longer to travel. Wished we had taken them out even more.
3)Learn a language in high school
4) Make a very concerted effort to learn some of the language. I always have been sure to learn the "polite phrases". Now I try to really learn a lot more.
5)If there is something on a trip I'd like to do, within reason, do it regardless how pricey I think it is.
6)Everything is easy, when you've done it once.
7) Worry less. There are nice people everywhere in the world.

@Bruce, I save all the little scraps of paper that locals have drawn maps or diagrams for me on. I will ask for help and my foreign language skills are horrific. I've had really wonderful interactions with locals this way.

“Sometimes I think I don't even know now some of what I knew back then.”

Same here Kent! ... 😂

Pack lightly! On my first trip to Europe in the 70’s, I took a large suitcase and filled it with as much clothes as I could fit in it. On later trips, I took a huge backpack with an external frame. That was a mistake as well. Now I travel with a carry on size suitcase with wheels. I have so much more freedom and can travel easier and faster with it.

Definitely agree with "learn a MODERN language in high school". Latin is very helpful for English vocabulary, but they don't even speak it in Rome anymore. LOL

Unlike most on this forum, I think "Tuesday Belgium" tours are helpful for covering a lot of ground quickly and going to places I would never have gone to on my own. We took a "Russia and Northern Capitals" tour in 1990 that went to Stockholm and Copenhagen. I'm glad I saw these cities, but they were not on my bucket list and I have no desire to return. Quick overviews like these tours can give you a basic knowledge of a city's layout that helps in planning future longer, independent visits.

Although a one time occurrence does not set a precedence, the one important thing I took away from the first trip was not to rely on someone else, in case the person turns out to be a flake, a no-show who left you in the lurch. Depend on yourself as a solo traveler and your own planning, not on someone else, advice, presence, etc, when the guy doesn't show up.

I knew after that first trip that I would go back in two years in 1973 also in the summer after I had completed my studies, assuming the finances could afford a shoe string budget.

Not pack light but pack smarter and if that means lighter ok.

Not to be afraid of taking the train. We drove all over Italy on my first trip abroad. I like having a car for SOME parts of the trips but taking the train can be freeing.

Don't be embarrassed that you don't speak the language but try to learn even little phrases that don't require someone speak back in long sentences that you don't understand.

My travel lesson that I have learned is, “I rarely regret the money I do spend, but I have often regretted the money I DIDN’T spend.” This is especially true regarding hotels!

I had a chance to go to Ibiza during a month long backpacking trip in college but we turned down the opportunity. Now I think that foam party might have been a great memory and I have zero desire to visit Ibiza now in my 40's. I would also tell myself that if I see something interesting or something I would like to purchase, do it then. I can't recall how many times I couldn't find the site or the shop again and regretted it.

Lesson learned. I will never share a room with a stranger again. Will gladly pay the single supplement. A bad roommate can almost ruin a trip!

1. Go to the gym and do a full cardio workout before your transatlantic flight.

2. Keep the shade open for the entire flight to enjoy view outside the window.

3. Always carry bottled water onto a flight.

Travel more, no one is on their death bed saying they wish they worked more.

Don't wait until you're older to travel, when you have more money, when the kids are older or grown up, or when you have more time; life will always get in the way if you don't make traveling the world a priority.

Take the kids, it's worth the effort and they'll thank you later. Bonus, you get to see the world through their eyes too!

Pack lighter than you think, if you need something more, stores exist where you'll be and you can buy it; basically don't pack for the what if's - what if I have a fancy dinner? what if it gets too cold? what if my flip flips break? Buy it if you need it, or layer, or make do without....just don't over pack, the what if's rarely happen.

You don't have to see it all this trip, you'll be back...

I would tell myself to not plan every.single.minute. I tried to do it on my first trip and couldn't keep up. I now enjoy being spontaneous and be flexible.

I like Bob Seger's reversal, in one of his earlier songs: Wish I didn't know now what I didn't know then.

Bob Seger vs Rod Stewart. Are we having a classic rock Faces off?

"And I said next time, next time, we'll get it right."

• I have few regrets, but not taking advantage of study abroad programs when I was young and free is definitely one of them.
• Traveling alone is not scary, eating alone is not scary (though admittedly, I still don't like it), paying the single supplement is usually worth it
• Keep a journal or blog, to document in real time. I enjoy reading them many years later and am reminded of the little things that made me so happy in the moment. Much needed in years when I cannot travel.
• Still a work in progress, when you do get lost, stop moving, take a deep breath, and don't panic.
• Sit and be quiet every day - in a church, park, or your hotel room. Your brain needs a break from all the new input.

I actually wish I could still travel the way I did when I was younger - hitchhiking everywhere in Europe in the 1970s. It was such a great adventure.

Faces! Good one, Karen!

In certain ways it was much simpler traveling in the 1970s, easily done without the internet and the electronic gear.

Conversely, thanks to the electronics in some ways , traveling is now more convenient, a lot easier, and tourist friendly, if that is important to you.

True that when a museum is super crowded (who hasn't come across that?), that does subtract from the enjoyment as dealing with crowds can get pretty tedious. Obviously, it also depends on the museum.

If I happen to arrive at the top priority museum in the summer, and within a few minutes two tour buses pull in, no way is that going to deter me from staying and seeing the museum, as if they had not arrived.

Now that you've inserted this song into my brain where it's been rattling around for 3 days, I want to extend to you my heartfelt thanks. ; )

Ooh la la!

My lessons learned include:

1. Pack really light, the lighter the better. Carry only a bag that fits any airline's carry on limit. I'm down to a shoulder bag with no more than 12 lbs total (usually about ten) and couldn't be happier. Two extra pants, a pair of warm ups and flip flops (for pajamas and/or laundry day), four or five extra shirts, four extra pairs socks and underwear, maybe an extra warm layer, a bag each for liquid and dry toiletries, some flight/hostel things (ear plugs, eye shades and blow up pillow) and a charger/plug converter for my phone. No camera, clock, GPS or other electronics (all apps in the phone). No unneeded paperwork or books (buy kindle versions of travel guides). Keep your reservations in your phone and put back up copies in an email to yourself. Only one pair of shoes that can dress up or down. The rain shell on my back. Downside is regular laundry; upside is never lugging heavy/bulky bags.

2. Never take a bus tour. I took one bus tour in the UK. They lost me when we spent 3 1/2 hours at Gretna Green - nothing more than a tourist trap - but didn't have time for more than a minute stop in the parking lot of nearby Jedburgh Abbey. Travel according to your own priorities.

3. Cruise excursions are inefficient wastes of money. Anything you can do on an excursion can be done more efficiently (both cost and time) on your own. If nothing else, find a local guide who will give you the same tour for half the price the cruise is charging - without a 60 person bus.

4. Know everything that's available, then do what interests you. I plan, doggedly, so I'll know all the options but am not driven to follow any itinerary doggedly. Plan ahead, stay flexible on the ground.

5. You don't need reservations. Part of not sticking to a dogged itinerary is to leave as much of your trip unreserved as possible. It's not hard to find a place to stay. If you don't have your heart set on staying at a particular place, there will be availability when you arrive. I even found a pension in Munich on opening day of Oktoberfest (but that's one where I would recommend a reservation).

6. TI's are trying to sell the products/services of the companies that pay them. Don't rely on TI's to get good budget conscious recommendations. Do stop by and ask if there are any special events that wouldn't normally show up in your pre-trip research. The best budget conscious advice you will get is from the young people who work at a local hostel. You don't have to stay there to go in and ask a question.

7. Your screw ups will likely end up being your best memories. Probably because it forces you out of your comfort zone.

8. The locals are much more friendly and polite when you are friendly and polite.

Great comments, Brad! The only minor disagreement I would have is that depending on time of year or popularity of the location, it might be good to have some reservations. It is disappointing that TIs are not always helpful and are really there to sell tickets and tours, that was one thing I didn't immediately catch on to during my first trip to Europe.

If you have a carryon and checked suitcase-always put a change of clothes in the carryon. Not only could your checked baggage get lost and you end up wearing the same clothes for days, but in case you spill something on yourself during the flight over or back you can change. A man sitting next to me knocked over my orange juice which spilled onto my white blouse and black slacks. I didn't have any clothes in my carryon so I had had to sit with orange juice stains on my blouse and slacks until we got to the hotel. The funny part was the guy got mad at me because a spot of juice got on his sleeves, meanwhile I'm covered with juice.

Always make sure you have directions to your hotel written down that you can understand and possibly tell to others. I arrived in Barcelona at night and I couldn't find my hotel, after asking several people who vaguely pointed in one direction and wandering around for 30 minutes, I finally found it as the sign was discreetly placed on the building. Combined with jet lag, it was not my finest moment and I must have looked like a frazzled mess when I arrived at the reservation desk.

Don't push yourself. If you want to sleep in, sleep in-don't feel you have to keep to your itinerary.

If in a foreign country, always have the correct name of a attraction. In Istanbul we walked all over Fatima, asking people where the Chora Church was. The first person looked at us and shrugged. We finally found a young man who spoke some English but had never heard of Chora Church. I brought out my guide which showed the church and he explained that it's called another name in Turkey. (Can't remember).

My first trip in 1992 was textbook what-not-to-do. I packed 3 bags for a three-week trip. I had no idea what Paris had to offer beyond the obvious. My only guidebook was ETTBD which was great as a general overview (more accurately, the 10% of it that I read) but not very helpful when boots were on the ground. I wore jeans in Italy in July. I didn't bother to learn the local polite words. And I think I accidentally set fire to a great public building. But I did fly open-jaws!

A lot of lessons learned here. Agree that educating yourself and planning is quite worth the effort. Yes, write down directions and other key information. Cell phone batteries die at the worst possible time.

These are great tips! Thanks to the OP! We're going to Europe for the first time in May. We've done a fair amount of travel, just haven't made it across the pond yet.

• I've learned to travel light - and I still haven't mastered 'light enough' - there's always something to pare back more!
• I like to make a long agenda of things to do, but think of them as options to choose from, and be ready to ditch any that are onerous in the moment. I.e., if we're running short on time or feeling sluggish, pick one or two that are in close proximity and really enjoy them. Those that remain on the list are reasons to return to the destination later.
• I think of the adage "you're not fully dressed without a smile" and my dad saying "you can catch more flies with honey than vinegar" and make sure that I'm ready to smile, be optimistic and let the small stuff roll off my shoulders. Being grumpy never helps the situation - and there are plenty of things to be grumpy about while traveling if you look for them (lines, late flights, poor food options, dry air, etc.)
• Remember that experiences provide more long term happiness than 'stuff'. Even bad experiences provide us with shared memories - and become less 'bad' with each re-telling. Like the time I realized I had a severe case of diarrhea as I was getting out of the water after a night scuba dive and had to put my gear way and then ascend three flights of stairs to get to my room ... seriously no fun in the moment, but funnier each time I relate it (even to non-divers!).
• List item

I agree completely about kicking myself for not studying abroad. If you’re a student or a parent of one, drop everything now and look into it.

I agree with pack smart and that doesn’t mean carry on only. Checking a bag isn’t the sign of the apocalypse. Packing smart is remembering that this isn’t a USA road trip where you throw everything into the trunk of a huge car.

I agree it’s good to do a lot of research beforehand. That gives you more flexibility when you’re at your destination, allowing you to adapt to the weather and your own energy level. However, please don’t plan your trip like a military exercise. I cringe when I read itineraries that are planned down to the wake up time in the am.

This advice applies to singles: go on a date if the opportunity presents itself. I’ve gone on dates with both Europeans and Americans I’ve met abroad. Trust me, you’ll remember them far more than any cathedral or museum.

If I were advising starting college students who have any or a distinct interest in going to Europe before turning 25 (the earlier the better), I would urge them, if presumably serious, to start studying a foreign language, preferably as a freshman, regardless what the major is.

Forget about that piece of info in the college/university catalog stating the major/field of study has no foreign language requirement. That may very well be true, but so what, but to the student I would say, it's also irrelevant.

Choose a foreign language and stick to it, be it French, Russian, Italian, German, Spanish, and basically pound away at it, (one cannot over learn) using which ever method, way or a combination that enhances your learning and retention, electronic aids, an exchange program, textbooks, computers, the "drill and and kill" method, etc etc. so that the student can speak, read and write with equal skill, ie know the "stuff" backwards and forwards.

Let's add:

1. Don't forget sleep and nutrition as part of your itinerary. If you run yourself ragged, you're going to get sick and won't enjoy your trip.

Drink lots of water. When you eat, try to make it something that gives your body both fuel and nutrition. Don't skip the churro and chocolate, but eat good meals too.

Unless you're in your 20's, staying up till dawn then hitting the road first thing in the morning won't be sustainable. Your body and mind need rest.

Don't fear things that are outside your experience. Use common sense, but embrace the unknown.
Stay away from crowded places and things.
Go to places that are not famous. When you tell friends and co-workers where you're headed, if they look at you like you're crazy, ask questions like "why would you want to go there?" or (even better) "where's that?" you know you're on the right track.
Spend the money. You can always get more money, you can't get more time.
Places that are hard to get to are usually worth the time and effort it takes to get there.
Speaking a foreign language badly (even really badly) is fine, people appreciate it, and it sure beats not speaking at all.
Never miss a chance to collect Frequent Flyer miles.
There are wonderful people everywhere, and you have a lot in common. They love their kids, they love good food, they want a good life, they're pretty much just like you. Go hang out with them and see how much alike we all are.
The quality of the adventure you will have is often inversely proportional to the size of the last plane that gets you there.
Don't look back, don't have regrets, life is short.

This has been the most helpful thread on this forum to date! I especially appreciate the comments about the single supplement. At the end of the day, I need to decompress and I need my alone time. I don't want to deal with sharing a room with a stranger, their habits, snoring, etc. :) Will be worth every penny on my upcoming GAS tour.

I didn't have the opportunity to travel internationally until I was in my late 40's, but I still made some classic mistakes.
1. Took a tour that covered 8 countries in 20 days - never again
2. Over packing - I still don't pack as lightly as I'd like, but at least I'm down to a rollaboard
3. Thinking "oh, no worries. We'll figure it out". A little planning/research can prevent a lot of problems.

We still make mistakes. In Yorkshire, we had the opportunity to go to a school fete. Did we go, no. Were we idiots, yes.

The best thing you can pack when you travel is your sense of humor.

I'm feeling pretty nostalgic, so forgive the long post....

I was super lucky that my father loved to travel and was an amazing travel companion. My first overseas trip with him @ the age of 10 was a 6-week summer trip to Europe--which started with a week in Paris and continued via train and ship to 4 other countries. What I learned on that trip I have never forgotten...

1) Don't be afraid to speak a foreign language, it's a great ice breaker and you learn something new every day
2) Be polite, gracious and mindful that you are in some else's backyard. Say thank you (a lot) to your hosts, also to your parents, sig other, whoever you are traveling with--be grateful of who you're with & what you're experiencing
3) Try new foods (even if they look weird) but never stuff yourself--nothing is worse than a stomach ache on a trip!
4) Be ready to Walk a lot on cobblestones (so you can eat ice cream every day--and I did :) so you better have comfortable shoes
5) Write in a little note pad ( doesn't matter what, just write what stood out or you did that day)--those old note pads become a precious connection to your youth
6) Know where you're traveling and pack appropriately--just because it's summer it doesn't mean it won't get cold
7) Don't take any day for granted, you never know if you get to go back to the same place with the same person.
8) Take lots of pictures--and make sure you frame some of them ( I still have the first pic I took of my father @ the Eiffel tower next to the last picture I took of him)

What I have learned since as an adult who likes to travel is that

1) You may never have the same leisurely pace or time that you did when you were traveling with your parents--so again enjoy every minute of every day you get to travel someplace new with your family
2) On that same vein, if you can squeeze another day or two into your trip, do it, it may be hard ( work, budget, other obligations), but DO IT, again--you don't know if you will have the chance to go back to the same spot with the same person/people,... you're never going to miss extra days at work, but boy if you only had that extra day in Paris, or Brighton or wherever ...
3) If you're traveling with friends, Make sure you know them before you embark on a journey with them---nothing takes the joy out of trip faster than an ill-matched travel companion---If you like to chill and your friends like to be on the go and cover a lot of territories, you will have problems.
4)Buy a little something to commemorate your trip--they help me anchor a moment that encapsulated something special about that particular trip ( it could be a magnet, it could be a ring, it could be a keyring or anything you like)..
5) Almost forgot, PACK LIGHT!! don't waste your time and your shoulders dragging suitcases from place to place--pack light and leave room for souvenirs

6) Stay hydrated, water is more important than food when you are traveling
7) Have a realistic budget for your trip (especially for those long haul ones)

My singular motto to my younger self would be---BE grateful that you can travel, make sure you do so with people you adore, travel as much as you can comfortably afford and add one more day.

FF, those are very helpful thoughts. Thank you.

I'd add that things will go wrong on occasion, so keep your sense of humor and go with the flow.

It really is a good idea to have a day or two at the end of a trip. An unscheduled day to wander and relax without having to be anywhere at a certain time.

Thank you BigMike--- I agree that a sense of humor is essential for young and the young @ heart : )

1. If there is something you really want (some perfect souvenir your little heart desires) buy it...The store may be closed the next day and you are leaving town and will be s*** out of luck. Still remember a piece of pottery in Galway.

2. Don't feel like you need to buy souvenirs for family and friends. They just get thrown away and your suitcase if full.

I agree with Nancy. My sister and I were on a tour in Granada 49 ( Yikes!) years ago and were in a small place where they made the inlaid wood items. My sister wanted to get a jewelry box. I said ‘wait until later. You will probably see them elsewhere and cheaper’ . Well, of course she saw nothing nearly as nice and she ended up having to go find the little place on her own to purchase it. Fortunately she is fluent in Spanish and was able to find it.

1. If you want to buy something, buy it then and there. You won’t come back. Something will come up/Your plans will change/You’ll return to the hotel another way/You’ll forget where the shop was. Just buy it.

2. Always try to find the restaurants with no English menu.

3. Remove 50% of what you packed before you go. You can live without it. When you think back on your trip, you won’t remember that you didn’t have that one specific sweater or how many shoes you took. But you’ll remember what an idiot you were lugging a full size suitcase through Santorini and how foolish you felt when you got home and realized you only wore 1/3 of what you took.

4. Always walk away from the tourist zone. Always. Find a neighborhood street or square, and sit on a park bench or at a café, preferably in late afternoon. Watch and listen. You’ll remember all the times you did this in much more detail and with greater fondness than almost anything else on your travels.

5. Smile at people even when you’re stressed or lost. Learn a few phrase in the local language and don’t be afraid to use it. People will often switch to English when they see you’re struggling.

6. Above all else, comfortable shoes! Sounds simple, but it took me much too long to drill that in my head.

I will add to this thread with my lessons learned from my solo, non Rick Steves tour from 2018. Went to England, France, Belgium and The Netherlands for a total of 2 weeks.

• Start a travel blog and post every few days while things are fresh in your mind. Acts as both a diary for yourself and a way to share your travel updates with friends and family. I used Blogger from my phone and had no issues. Keeps you from having to lug around a notebook/pad, too.
• If you book any tours through third party sites like Expedia, confirm the meet up location 1-2 weeks before your trip. I had booked a trip for 'Wine and cheese tasting in a Paris cellar'. When I got there, the guy said the meeting site had changed a month or so prior, but nobody told me. Got a refund, but still aggravating. Took the time to wander around Paris, so not a total loss.
• Don't be afraid or embarrassed to ask for help--information kiosks are great and typically have folks who speak English.
• If something doesn't feel safe, it probably isn't. I was sitting on a bench near the Arc de Triomphe taking a break when two men approached me. I could see they were saying "you go behind her; I'll go in front of her" before they approached, which was weird. Not sure what they were plotting, but I got up and walked away as quickly as possible.
• Use Yelp (I am both a reviewer and user of the app) to seek out great places that may not be in guidebooks or on main streets. I found a cute little off the beaten path crepe place and had a lovely lunch. It was a tiny mom and pop and one of the regulars was shocked at how I found the place. The waiter was a curmudgeon, but I got a sweet crepe, savory crepe and cider for 10 Euros. I forgot that coffee with meals was not the norm and got a funny look when I asked for coffee or tea. :)
• Always have a few Euro coins on hand for public bathrooms
  
• I will emphasize the 'pack light' mantra. Thankfully, I've had a lot of practice with work trips. Only took the RS Convertible Carry on (used as backpack) and a day bag. Recommend watching Sarah Murdoch's Packing Light and Right video, too.
• Make packing, planning/prep, itinerary and budget sheets and plan several months in advance. But also be prepared with a sense of humor and flexibility because things will go 'wrong.' I had my Uber go to the wrong address for my group Louvre tour and missed the meeting time. However, it worked out fine and I got a refund. I just went to see what 'I' wanted to see and enjoyed a lovely lunch at a restaurant in the museum.
• Dryers in homes (e.g., Airbnb) SUCK because they don't vent to the outside takes 2-3x longer to dry than dryers in the U.S. Also, always wash in cold and hang dry if needed, or use launderettes if possible. Nice time to chill with a cup of coffee and people watch, too.
• Yes, you can buy most things over there, but some toiletries you can't. Ladies, bring your own preferred hygiene products. If you wear contacts, and you see (preferably a travel size) version of your favorite solution, BUY IT. Was reasonably priced in the UK (it's never really cheap anywhere, but if you need it, you need it.) I'm unfortunately not able to use daily contact lenses.
• Don't bring hard copies of things unless absolutely necessary. Save things in your email, on Google Drive or otherwise.
• I know I'm contradicting RS here, but don't use public wifi if you can help it. Many of the mobile companies connect to networks in Europe and the 3G you get is just fine (I paid $25/week with Sprint). I didn't use wifi at all in Europe. Public wifi is not secure, especially if you need to pay bills online when you are traveling.

Pack light and then take things out. Go as minimal as possible.

Splurge on experiences. My absolute best days were when I’ve hired a private guide to take me around and teach me about their city and culture.

Don’t rush. Prioritize the top 2-3 must do things and relax and enjoy where you are.

Be alert on public transport. I was pickpocketed in Amsterdam on the tram because I was so enamored with the city I let my guard down.

What Jill says above about contact lens solutions. For RGP, at least, they're yipes expensive in Europe, plus hard to find. After the lost-luggage experience arriving in Madrid several yrs ago, lens solution is now in my carry-on every time.

Larger picture - seize the day, the souvenir, the quirky side street, the chance conversation no matter how awkward your French/whatever; go everywhere when you've got the energy, be brave and take a cafe table or even a nap when you don't. Opt out of whatever when you hear the call of a vacation from your vacation, Rick's great phrase.

Pack cold meds and whatever photo back-up equipment's applicable. We've all got stories...

Keep a journal!

If you use Global Entry, and are older, make sure you hydrate before using the fingerprint kiosk. When you are dehydrated after a long flight, it makes it harder for the machine to read your fingerprints.

"Travel is the only thing you spend money on and end up richer." Said originally by someone way smarter than me. I will skimp and save at home so I can spend it when I travel. On our first trip to Europe, we skipped a number of museums because they seemed too expensive. I remind myself airfare to go back to see the museum is even more expensive. I no longer have any problem whipping out the credit card when I travel (or the cash...). I'd rather eat rice and beans and skip the restaurant meals at home than try to skimp and save when I travel. It's much easier at home to be frugal.