I wanted to share this article from Tom Watson, one of the games greatest players.

Getting into a good position at the top is important because it sets you up to make the proper downswing from inside the target line into the ball. An easy way to learn what a good position at the top feels like is to do this simple exercise:

Address the ball as you normally would, bending over at the waist, with your arms and knees slightly flexed (photo 1). Then, while maintaining your address posture, lift the club and lay it on your right shoulder next to your neck, with your elbows bent and close together (2). Now turn your shoulders and hips away from the target exactly as you would if you were making a full backswing (3). When your turn is complete, simply extend your left arm out until it's nearly straight (4).

Now you're in a good position at the top of your swing. Practice this whenever you can -- you can even do it at home in front of a mirror -- so when it comes time to play, swinging into the proper backswing position will feel like second nature.