Understand and identify your swing faults (if you have any) and the physical limitations that may cause them. Swing faults, which are technical flaws in your golf swing, can be can be caused from physical limitations and or from improper swing mechanics such as lack strength and inflexibility in critical areas of the body.
Everything you do before you set up determines how well you hit the ball. If your posture is incorrect, then it is difficult to make a full turn and keep your body angles throughout your swing. Try this simple posture drill to improve your pre-swing fundamentals.