Here are some of the things i do.
i will preface this by stating i fly solo so that by itself can save $$$.
I look for central places to stay relative to where all of the things im going to see/do. That way i can try and do more walking and do my daily trips in a radial fashion. As far as price goes i try to keep the cost to < 100 USD per night. So far i havent spent any time in any hostels, but that may change. But i dont mind spending a night or 2 in an EasyHotel. They are like a dorm room for any of you that have had the chance. To me its just a place to sleep, take a crap and shower. I know for others, its their "Castle" and it has to be one, but for me, i spend < 8 hours in it and so i dont mind a sparse room/lodging.
sometimes i cant get a central place to stay at the rate i want so i do the next best thing and look for the closest place at the price im willing to pay. I also look for a place close to a transportation hub/line to minimze my time in transit.
I dont eat large meals anymore due to my work schedule. I keep that meal schedule during my trips so that i dont need to change once i get back. I also eat when conveient. IE. If im in a museum at lunchtime, i will keep on touring until i come across a cafe or if one isnt present where im at, then i wait until im done and go see some food. I love soup and sandwiches, so as you can guess, they usually arent that expensive. Also, if i eat later than normal, that will throw off my other meals for the day so i usually end up not eating a large dinner. I will also buy food in grocery stores along with drinks. As far a drinks go, i will try to get a larger container of juice. Most juices will survive 1 or 2 days w/o chilling and ive usually consumed it by the 2nd day.
I bring a camelback water bottle with me and fill it up with tap water. so far all of the places i go to have potable water. I dont carry this with me when im in town unless im just chilling, but i do keep it in my room and use it on my flight/train.
This is a difficult one. but i spend alot of time looking at different routes to where i want to go and where i will stay. Also, compare train vs air. I will take the bus, but it has to be the only way of travel or the fastest. when it comes to train vs air, i place approximately a 4 hour limit on my train before i look at air. Its MY limits only and something that can change depending on what going on. Example, i want to take the express train from Moscow to St Petes this year and its a 4+ hour train ride. Air is faster, but more $$ but i want to take the train so the train it is. I will buy my tickets ASAP since i want to make sure i make it to where i have plans or reservations. Some places i will buy the ticket when im there, but some places not. Its just a matter of research and if those runs are packed.