The best method I have found for teaching a golfer to hit the ball "from the inside-out" is to establish a mental picture of the top of the backswing as being just about the position in which a waiter carries a trayful of dishes. He carries the tray with his right palm up, and that is relatively the position for the right hand in the perfect golf swing.
The start of the swing is very important in getting you to the proper "waiter's position." The golfer who wants to overcome the common habit of hitting from the top or of hitting from the outside-in and slicing the shot can establish the mental picture of the waiter very easily. The swing should be started with the right elbow tucked well into the side and it should be kept as close to that position as possible during the backswing.
The waiter's position sets up a slight reverse hand-action as the club starts down. From this position the player can move into the shot and be sure of staying inside the ball (or hitting from the inside-out, as the expression goes). This also keeps a player from expending his power too soon and brings him into the hitting area in an excellent position to strike the ball accurately and forcefully.
from JOHN THOREN, Myopia Hunt Club, S. Hamilton, Mass.