A bad grip has wrecked many a golf game. It can cause hooks and slices and increase the natural tendency of most golfers to use their right arm in too strong a fashion. I advocate gripping the club in the palm of the left hand, not the fingers. If you get all of the grip from the fingers, it increases the chances of letting your wrist bend. A lot of golfers tend to let their right hand slip around toward the bottom of the shaft because it makes the arm feel stronger. That's the thing you should be trying to get away from—that feeling of power in the right arm. If the right arm slips toward the bottom of the shaft, it leads you to pick the club up drastically on the backswing. The result is you smother the ball. Some golfers start off with a correct right hand grip but they don't maintain this correct grip throughout the backswing. This causes the golfer to close the face of his club as it reaches the ball, and a hook results.
Turning to the left hand: this is where the slice begins. Gripping the club too much in the fingers makes the wrist collapse on the backswing. This opens the club face and a slice results.
A rule of thumb works something like this: If you're slicing, look at your left hand and see if the wrist is collapsing. If you're hooking, reappraise your right hand grip.
from WILLIE KLEIN for all golfers except low-handicap players