This tip is a simple drill I use frequently when I get out of sync. It mostly helps my rhythm - feeling the club go back and through - and clears my head of any real swing thoughts. Others say it helps them with weight shift.
Set fix or six balls on the ground a foot or so apart. Take your stance as if you were addressing a ball one foot left of the far left ball. Swing back and simultaneously step forward with your right foot. As you begin your downswing, step forward with your left foot so that you're in a good position to hit the first ball. Hit it, finish your follow through, and then take a step with your right foot again, bringing the club back down and through and into another backswing. Step forward with the left foot and swing through the ball.
Keep stepping down the line, hitting a ball with each step. You'll be surprised how easy it is to groove a comfortable, free-flowing swing and make solid contact each time.