Wind it up: Try to coil your upper body against a stable lower body. Don't let your left leg collapse.
One of the keys to hitting powerful shots is the "stretch factor" in your backswing. A big windup of the upper body against a stable lower body creates torsion and the energy needed to produce a lot of clubhead speed.
The sensation of winding your right side away from your left side helps maximize stretch and coil (above, left). Feeling some resistance in your left leg as you turn to the top (from your foot up to your knee) is a great way to monitor stability—and get more stretch.
Also, check to see that you've maintained a good gap between your knees; don't let your left knee cave in (above, right). Here is what you have to remember: Winding up your body—not just turning—is what sets up a powerful downswing.
Curtis Strange got behind it
Two-time U.S. Open winner Curtis Strange depicts a top-of-backswing position that's perfect for many golfers to copy. There's a trend today to stay more centered and keep your head still on the backswing. Most golfers, however, lack motion in their swings. As long as your right leg remains fixed, you can allow your head to move slightly to the right as you make a full turn and load your weight into your right side. This is particularly important with a driver, as it allows you to stay behind the ball and sweep it off the tee.
David Leadbetter is a Golf Digest Teaching Professional based at ChampionsGate near Orlando. He operates 26 golf academies worldwide.