Forget about turning the shoulders around the spine. This can lead to a right shoulder push, getting your hands outside plane (creating an outside in swing).

Assuming you're a right handed golfer, take your left upper arm (bicep/tricep) and use it to take the club away. Use it to pull the shoulder across your body, so to speak. This will automatically create the coil. The more you can 'pull' with your upper arm, the more coil you'll get.

For drilling purposes, work on keeping your right side totally quiet (again, assuming a RH golfer). Don't pull or push with your right hand, arm, or shoulder. Keep it all left-actuated; both the takeaway and the downswing - your right arm is just along for the ride, there to keep your divot slightly ahead of center.

This works for all clubs. If you like a different feel for different clubs (ie woods vs irons), you can pick your upper arm up higher for irons (promoting a steeper attack), and take it away lower and longer for woods (to promote a sweep).

This method has worked quite well for me, and has gone as far as creating great shape in my iron shots (wedge flight paths are almost parabolic), and my drive is now a long penetrating flight.

Just my .02