For the average golfer, the grip is probably the most overlooked fundamental, yet it's one of the most important techniques to good golf.
An incorrect grip, especially one that's too weak, sets up a chain reaction that makes it difficult (if not impossible) to hit the ball straight and with any reasonable distance.
A weak grip is created when your hands are turned too far to the left on the club, and the club sits too high in the palm of your left hand. You'll know your grip is too weak when your thumbs align straight down the shaft and the "V"s created by your thumbs and index fingers point directly up at your chin.
Perhaps one of the easiest ways to know if you have a weak grip or not is if it only takes a few rounds to wear a hole in your glove on the fleshy pad on the heel, you're holding the club too high in your palm. If you're going through gloves as quickly as you're probably going through balls, better take a close look at how you're holding the club.
A weak grip creates an open clubface throughout the swing, further compounded by the tendency to roll the clubface open during the takeaway when the hands are turned too far to the left. More often than not, golfers will try to compensate for this move instinctually by altering their downswing path to the left to get back to the target. What you get is a glancing blow and a nasty slice or a pull, depending on the position of the clubface at impact.
In addition, you'll lose distance when the grip is too high in the palm of the left hand because your wrists aren't allowed to hinge properly, which, in turn, reduces the leverage that creates club speed at the bottom of your swing.
So how do you fix this problem?
Try this. Stand up straight with your arms hanging comfortably at your sides. Notice how your hands naturally turn in so that the palms point more behind you and your thumbs touch your sides? Take your club in your left hand and allow the grip to rest down in the fingers. Create a stronger grip by making sure that your left hand remains turned slightly to the right, just as it was before you gripped the club.
As you position your left hand onto the club, check the clubface to make sure the leading edge remains in a square position. Once you've done that, match your right hand to the left by fitting the left thumb snugly underneath the lifeline of your right palm. When you close your hand, the heel pad should rest on top of the grip.
Now take a stance where you are addressing the ball. If all is well, you should see two to three knuckles when you look down at your grip and the "V"s created by your thumbs and index fingers should point toward your right shoulder. Make sure your grip isn't too strong. You'll know if it's too strong if you can see three or more knuckles at address or if the "V"s point right of your shoulder, turn your hands to the left until you get the proper alignment.
Here's a little practice drill that can help--try this on the practice tee.
Start by strengthen your grip by turning your hands more to the right as we discussed above, but also close your stance slightly by dropping your right foot behind the left. Once you are in this "incorrect" position, swing along your body line back and through to encourage the proper swing path. Do not try and hold the club through the impact area. Be sure to rotate your right arm over your left once contact is made to close the face through the hitting area. When you start hooking the ball, square your stance and hit a few more balls. You should see a dramatic improvment.