Developing a proper grip requires a sound understanding of how the placement of the hands impacts the direction of the clubface and the wrists throughout the swing. It is also important to understand how the hands connect on the club and how the various grip types allow you to vary your ball flight. I would encourage you to experiment with the grip types shown below, and learn to incorporate slight variation for your specialty shots.
Grip type #1: The weak grip
The weak grip has been classified as "weak" because of the limitations it places on wrist action, and the effects it has on the loft of the club. As you look at the pictures of the different grip types notice how the weak grip starts with the back of the left hand virtually flat, and the right hand very much on top. From this position, the club usually ends up in a very open position that encourages an outside-in swing path. As a result, most golfers slice their shots with this grip, and lack distance as a result of the excessive side-spin imparted on the ball at impact. With this being said, it's a good idea to avoid this grip type unless you are intentionally slicing a shot, or struggling with a chronic hook.
Grip type #2: The modern grip
The modern grip has been used by many generations of golfers and represents the standard in terms of recommended hand placement. Notice how the logo on my glove is now visible, and the left arm is virtually in line with the shaft. Along with this, it is important to point out that both hands are positioned so that they can pressure the club from a position that is slightly right of center. From here, the wrists hinge the necessary amount, and the clubface has a better chance to stay square to the arc throughout the swing. As a result, the clubface strikes the ball with less side spin and allows you to transfer energy more consistently at impact.
Grip type #3: The strong grip
The strong grip has been classified as "strong" due to the effects it has on the clubface and the wrist action during the swing. Notice how the hands are both positioned well right of center, and how you can see more inward pressure from my left wrist. From here, the clubface usually ends up in a closed position throughout the swing which de-lofts the club at impact. As a result, shots generally travel longer because the club is hitting the ball with less loft and the wrists generate more club speed from this position. The only downside to this grip is that the clubs with less loft become difficult to flight, and the ball tends to travel with excessive hook spin. With this being said, golfers that struggle with an open clubface and limited wrist action should give this a try.
CONNECTING THE HANDS With respect to connecting the hands it is important to use whichever method gives you the best feel for keeping your hands together during the swing. Listed below are the most common methods of connecting the hands.
Be sure to experiment with all three to get a better sense of what works best for you. Connecting the hands typically involves one of the three methods shown above. Over the years, the overlap method has been the most popular, although the interlock has been used by a number of players including Jack Nicklaus and Tiger Woods who prefer intertwining their hands on the club. The 10-finger method is yet another way to connect the hands on the club for players with smaller hands that have difficulty using the overlap and interlock method. All three methods work well, and it is important to choose the method that allows you to maintain a consistent connection between the hands for the duration of the swing.
Now that you have a better understanding of the grip types I will now discuss the proper positioning for the left and right hand on the modern grip.
POSITION THE LEFT HAND Proper positioning of the left hand is as easy as following the pictures shown above. For starters, take notice of how the club appears secured against the base of the fingers in the first photo. To achieve this, be sure the club runs from the base of your pinky and through the middle of the index finger. Next, notice the thumb and the position of the knuckles in the second photo. This is how the modern grip appears in the left hand. The modern grip typically forms a V between the thumb and index finger that points to the right of center. If you copy these positions, you will have the ability to hinge your wrist both vertically and horizontally as shown in the third and fourth photo. As you go through these position checks, you will feel the fingers doing most of the work, and the palm applying a bit of downward pressure on the finger tips. It's a good idea to also try this with your left hand in a stronger position (more right of center) and also a weaker position (centered or even left of center) to feel the differences.
POSITIONING THE RIGHT HAND Proper positioning of the right hand starts with placing it against the side of the left thumb as shown in the first photo. From here, it's important to position the club diagonally across the middle of the index finger, and against the base of the middle two fingers as shown in the second photo. Notice how snug the middle two fingers appear, and the how the left thumb fits against the right palm with the index finger slightly triggered. As you complete the grip, the right thumb fits on the club slightly left of center and a V is formed between the thumb and index finger. From here, the hands have the best chance to work together as a team, and produce the necessary wrist action and power transfer during the swing.