It's been my experience that it is not beneficial to point out all his faults to a golfer but to try to isolate a key error he is making. If we can correct that one, we usually correct at the same time a good many subsidiary faults that spring from that major error.
Very often, assuming that a golfer's grip and stance are correct, where a good many players seem to go wrong fundamentally is turning the control of the swing over to the right hand and arm from the beginning of the stroke. I have long made it a point to suggest to my pupils that they spend some time on the practice fairway working on a tip I learned about a long time ago and still consider a first-class antidote for this particular error. What you do is take a towel, tie a knot in the middle of it and stick the knot under your right armpit. To keep the towel from falling to the ground as you move into your backswing, you must keep that right elbow fairly snugly against your right side. When you do this—and this is the point—your left arm and side have to take the club back. This is what they should do, of course.
This tip yields a golfer two other dividends. It helps you to develop a wide arc to your swing. It also builds the kind of action where your right arm and side are in an ideal position to swing through the ball as you enter the hitting area on the downswing.
from PALMER MAPLES, Benvenue Country Club, Rocky Mount, N.C.