Number RSVP cardS and log who has which number on a spreadsheet. Easiest way to track who still owes you an RSVP. When you don't get them back (and there will be many that you won't, its just how it goes) you know exactly who to confirm with.
This is how I plan on asking the maid of honor & bridesmaids. Really cute idea. 5 Creative ways to ask: Will you be my bridesmaid? This photo is a DIY balloon in a box that you have to pop to find a secret message inside!