So many golfers have good swings that do not repeat because of extraneous movement. One of the best ways to remove extra moving parts is to correct balance issues. Here is a great drill to help you feel/find your balance.
This is a very comprehensive drill because it creates a sensation that you should have on more than just your full swings. Utilize this "flat footed" approach in your putting, chipping, and bunker shots for more consistent contact and better results.
Tasha Bohlig, PGA shares some golf tips to help your game