Opening up your stance
I've heard several instructors say that for shots within 80 yards you need to have an open stance. Why is this and how open should the stance be?
On shorter shots, you are trying to limit the body move in the backswing so you do not hit the ball with full force and yet still allow the body to turn and "get out of the way" in the downswing. By opening up at address some (any where from 20-35 degrees) you easily achieve this.