Pretty straightforward- match up projects you want to do with the yarn you have. Pair up everything you possibly can. You'll probably have leftover projects, and a pile of yarn that doesn't quite fit anywhere in your goals, and that's fine. Just set all those aside. Assign a purpose to as much yarn as possible and write it down somewhere safe (if you've stashed it all on Ravelry, just put it in the notes). Now hopefully you'll be all excited about starting new projects that you ACTUALLY HAVE THE YARN FOR RIGHT THERE OMG!
(Maybe some pictures coming later. I am in a food semi-coma, so we'll see.)