I hear so much talk these days about making a full shoulder turn but restricting the hips. The thing is, most players need more hip turn to make a decent backswing. Even Greg Norman, who I worked with for years, focused on turning his hips, and he was the best driver I've ever seen.
Greg's swing thought on the backswing was, Right pocket back. That meant turning his right-front pant pocket behind him (above). He later simplified it to RPB, and that often was his last thought before starting his swing. For Greg, it allowed him to maximize his range of motion going back, but it has the added benefit of preventing a sway to the right--a common amateur fault. The sway not only reduces power, it makes it tough to get back in position to hit the ball.
If you think you need more windup--or you're drifting off the ball--try Greg's RPB. It'll free up your backswing and get you ripping your tee shots.
People always ask if they're swinging back far enough. Forget that. More important than backswing length is backswing width. Turn your body, and push your hands away from your head. Remember, the purpose of the backswing is to get in position to make an athletic move down. Turning and extending your arms will help you do that.