The return of serve is your most important shot of the rally. If you can get a good return of serve, you can catch your opponent off balance and more easily when the serve back.
Here, your goal should be, when you get into position for the return of serve, to do is start positioning yourself about a racquet length, and arm length from the back wall, about mid-court.
You should stand nice and comfortably by having little bend in the knees, racket in ready position. Remember, you should be in the middle of your stance, so you can easily go to your forehand or your backhand as necessary to respond a serve that comes from your opponent.