A lot of golfers tend to sway or slide off the golf ball which gives them a false sense of power.  In the correct backswing, the shoulders turn and the weight stays on the inside of the feet.  In this video, teaching professional Travis Nagel gives a great drill that will improve your backswing and create the proper feel of turning vs. swaying.

1. Feet together drill: Bring the feet together and place the ball in the middle.  Hit shots keeping the feet together focusing on tempo, balance and the feeling of turning.
2. One foot drill: For a more advanced drill, balance on one leg and place the ball directly in front of the grounded foot.  Once again, hit shots with your focus on balance, tempo and feeling a turn vs a slide.

For another great tip, check out this video on how to improve the takeaway and weight transfer in the golf swing.