From Donald Crawley, a Golf Magazine Top 100 teacher, director of The Boulders Golf Academy in Scottsdale, Ariz., and president of GolfSimplified:

Having trouble with your shoulder turn? Most turning problems stem from an incorrect and poor posture. Work on pulling your shoulder blades back, straightening your spine from tail bone to neck, and most of all lifting your chin off of your chest. Forget "keep your head down" and try to "keep your chin up." A better posture will improve your torso rotation and take care of that shoulder turn.