Best advice someone gave me that helped a ton, NUMBER your rsvp cards because some people write a no where they should put their name and you have no idea who it is! Once you get them back in the mail, go into your excel spreadsheet and mark them coming or not coming. Then you also dont have to worry about losing the cards and you can easily tell who still owes you one!
Number your RSVPs! Smartest advice I saw on Pinterest for wedding planning! Number the bottom of the RSVP card 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.