Get a small collapsible backpack like this: Patagonia Terravia Tote Bag Backpack 24L so you can have a few things on hand during train rides, and have the option to lock your main bag in a locker at the train station or your hotel room while you're exploring. In Italy (Germany as well, maybe France too, I have less experience there) there are often really nice, cheap public aquaplexes with saunas and pools and hot tubs, that can be a nice way to refresh that is less gross than a hostel bathroom. Have two wallets, one for little stuff with a coin pouch and one for larger sums and your passport. Italy and France are both pretty safe but... Still worth it. Always have wet wipes. Remember to validate your tickets in Italy.