The tendency I see with a lot of people is that the men are not flexible in their hips and shoulders, so they usually move off the ball in their backswing and come over the top on the downswing which is a huge power loss.
My women students, on the other hand, sometimes are too flexible in their hips and shoulders and tend to over-rotate during their backswing which is also a power loss. To correct this, we spend time learning to separate what the upper body is doing from the lower body to create a coil effect. Creating coil in your backswing will allow you to unleash your maximum amount of clubhead speed on the ball.
The ideal rotation is a shoulder turn of 90 degrees and a hip turn of 45 degrees. Almost all great ball strikers turn their shoulders twice as far as they turn their hips. To test your coil, swing back and stop at the top of your swing. Is your left shoulder over your right knee? If you are left-handed, your right shoulder should be over your left knee. If not, then you must work on training your body to make a better turn.
Here is a great exercise to learn this move:
Holding a medicine ball or a dumbbell with both hands in front of you, lunge your left leg back. Bending your right leg at 90 degrees and dropping your left knee as far as you can. Rotate the weight to the right, then to the left. Keep your hips facing forward. Perform 10 to 12 repetitions on each leg.