The Goal: Hit a draw
The thought that will let you achieve it: Feel like your left arm stalls as the clubhead approaches the ball.
How it works: By slowing down your left arm, you give your right arm and the shaft time to catch up so that the toe of the clubhead passes the heel, squaring and closing the clubface. Energy is passed through the shaft to the clubhead, adding speed and making it easier for you to turn the face over.
If there is tension in your left arm at address, there usually will be even more tension at impact. This restricts the rotation of your forearms and the clubface, making it difficult to draw the ball. Relax your left arm at address, and you will get the face rotation necessary to draw the ball and pick up a few more yards off the tee.
How to check your position at the top
Use a book to nail a critical moment in your swing
The position of the club at the top of your swing sets the stage for a solid downswing. Here's a way to check, using a small hardcover book: Grip the spine of the book in your fingers, and take your normal address. Now swing back to the top and freeze. Your right elbow should be slightly lower than your left, and your left wrist should be fairly flat, so that only the bottoms of the pages are visible to someone standing behind you. If your friend can see those pages and not the front cover, you're in perfect shape at the top. If he can see much of the cover, the clubface will be open at impact.