I have a small man's wallet only. It folds in half and has an ID window on one side. The other side has two slots and a pocket for cash. I keep my license in the ID spot and tuck any receipts I need under that. In the slots I keep one (sometimes two) debit card(s) and insurance cards (me, DS and DD). The pocket holds cash. I clean it out at least once a week in case it gets too stuffed. Oh- I also keep a teeny sheet of stickers for in a pinch amusing of my 2yr old!
I find smaller is better. If I need to take more, I swap stuff out or toss it into the diaper bag.