Thanks for the reminder. I'm going to have to find a money belt. But I still wonder about when one has to take out some cash and/or a card. Does one have to unbutton one's shirt (or pants) to reach in for the money belt or does one stash some money--or one's wallet--in one's front pockets? I'm assuming that in crowds or even in non-crowded areas, it's easy for "professional" or "semi-professional" pickpockets to reach in to one's daypack and pull something out.
Addressing your question to me personally :) Here are my suggestions.
This is what you should receive shortly from the Rick Steves group before your tour. - "What's Included" http://www.ricksteves.com/tours/italy/best-italy
With regard to pickpockets, they are around. They can work alone or in teams - a watcher, a distractor, a grabber or a picker - adults (young & old) & children (all ages.) Do not sign anything they throw your way. You must be firm in your stance. Just say, "No," & move on. If they ask you if you speak English, say, "No." They will probably know you are on to them. Do not fall for any found ring or leather jacket scam either. Walk on.
Personally, on the positive side, I had no trouble whatsoever. But, "they are out there," so just be aware of your surroundings & be street smart as much as possible. It is sad that we need to worry about all this on holiday. They look for targets; they prey on the tired, confused & distracted traveler. They watch for those who fumble with maps, cameras, bags, etc.
I know you mentioned you are traveling solo, but perhaps you may make a friend or two on the tour - sort of like a buddy system. Not to say you must hang with them 24/7 or vice versa.
Please read the thread of tourist scams to give you an idea of what goes on in the more populated attractions and transportation. http://www.ricksteves.com/travel-tips/theft-scams
For your "day" money and credit or debit card, there are a few ways you can carry them. I am not sure if you decided to carry a day pack, but if not, some men carry a cross body messenger bag so their daily valuables are accessible and protected in front of them. I do not think it is a good idea for anyone to put money in any pants pocket; even if it is 20 Euro. A day pack can be picked, so don't put valuables in it. A good thing about a messenger bag is that you do not need to remove if from your person when you sit or stand anywhere; more protected on your person.
Also, there is this: http://travelstore.ricksteves.com/catalog/index.cfm?fuseaction=product&theParentId=124&id=377
or this: http://travelstore.ricksteves.com/catalog/index.cfm?fuseaction=product&theParentId=124&id=157
If you are unsure about a money belt, maybe you can go to your local Super Walmart - check out their luggage section. They sell money belts there, not expensive. You can see if you would like it before you buy Rick's or anyone else's.
The neck pouch or other money belt can be for all your other monetary valuables. If you go that route, get some little sandwich baggies and put your money and card(s), passport in each one, to keep it dry in your money belt. Some like the belt loop pouch because you can put your day money/cards in there and flip it inside your pants. Paying for a little something, it is not disrobing, lol, or provocative to pull out that pouch and then flip it back in.
When you need to access your day money, I presume you won't be in the middle of a plaza taking out euro, you will most likely be in a cafe, store or larger restaurant to be more discreet. But again, be aware who is watching you. And, as I mentioned another time, get familiar with the Euro dollar and Euro coin. If you will pay for most things in Euro, don't worry about rushing to pay a merchant.