Great suggestions everybody!
The one recommendation I have for people that want to improve by learning others songs is to focus on the music that inspires you. So what if Joe Schmoe guitarist is the best ever, if you can't stand how he/she plays don't bother. If your favorite musician plays the same four chords over and over again, learn that. If you use this mentality to start out with you will be more willing to continue from the satisfaction of learning what you enjoy.