Most people with a slice problem cut across the ball on the downswing. To learn the correct path for the clubhead to follow, think of a rope attached to a tree above you. From the top of the backswing, you should feel that you're pulling the rope straight down. This forces the right elbow to stay close to your side. It also gives your stroke the correct inside path, and improves your ability to swing out toward the target rather than across the ball.