Fundamental 4 Use of the legs
By using the legs correctly in the back-swing a stable and balanced platform is created enabling a strong downswing. A wide platform is what you are after and not a narrow one. As your back-swing nears its completion the left knee has moved on a line between your shin and the ball. With the woods the left knee will move in behind the ball. As this is happening the right knee should move backward and away in a straightening manner. This is how a wide base is created. The action of the legs will increase your hip turn and in turn enable you a good shoulder turn.