If you continue to pull your putts to the left of the hole (right-handed golfers), the culprit may be that you are looking up to follow the path of the ball.
“How’s that?” you ask. As you watch the path of your putt with your eyes, your head moves and this motion causes your shoulders to turn, which may cause your putter face to close resulting in a missed putt to the left.
The quick and easy remedies are two-fold. First, start the habit of focusing upon the spot where the ball was for a couple of seconds. On short putts, you probably don’t want to even look up, but simply listen for the sound of the ball falling into the cup. Gary Player has employed this as his style for decades. The second thing you want to do is to keep the back of your target hand (left hand for right-handers) moving toward your target. If you are wearing a glove with velcro patch or emblem on it, picture that spot moving right down your target line. A smooth accelerating stroke in this manner will straighten you out in no time.
Contrary to popular belief, putting may about the only time you really want concentrate on “keeping your head down” as you play golf.