A common fault I see in the backswing is the arms lifting! We need to see the arms staying with the body as we take the club back. The right elbow shouldnt lift way from the body and should stay the same distance away from the chest as it started (roughly 3 fingers width). A great way to encourage this is to use your clothes to help you make the right movement.
Take a piece of your top from the right of your chest (right handed player) and tuck it under your right arm. This should encourage you to keep your right tighter to your body creating a good plane and connected swing.