To create the correct turn in the swing without excess motion and moving off the ball try this drill. From address pretend that there is a blimp above and behind your right shoulder. Turn back and look up at the blimp. On the forward swing pretend the blimp is up over your left shoulder and turn through looking up over the front shoulder. This motion which is a very centered and balanced turn is all you need in the swing. The body will turn correctly without excess motion or you trying to shift your weight. This will help you hit more solid and consistent.