A cross-handed putting grip is exactly that. It is a grip which sees you holding the putter handle with your hands crossed over from their usual, more common position.
For right handed golfers who would usually hold the handle of the golf club with their left hand at the very top and their right hand below this, a cross-handed grip sees their right hand at the top and their left hand below this.
To achieve this putting grip, take up your stance with your feet shoulder width apart. Align the putter face at the target line with your right hand. Now align your toes, knees, hips and shoulders parallel to the target line and position the golf ball in the centre of your stance. Ensure that your eyes are directly over the golf ball or just slightly on the inside of it. Maintain your balance and then position your right hand on the putter handle so that your right thumb is along the front of the grip pointing directly downwards. Wrap your fingers around the back of the putter handle.
Now place your left hand on the grip below your right. Again position your left thumb so that it is down the front of the handle pointing directly downwards and wrap your fingers around the back of the grip. Ensure that your hands are close together and that your left palm is sitting on top of your right thumb and allow your left little finger to interlock with your right index finger. When you make your putting stroke, lead with your left hand, arm and shoulder and use your left arm as a pendulum to swing the putter. This will ensure that the putter head swings along the target line improving your accuracy as you are simply using your left arm as a lever from your left shoulder and this is very easy and simple to control.
Putting using a cross-handed grip will improve your accuracy and the consistency of your strike and you will see a dramatic improvement if you are a very wristy putter at present. Using your wrists excessively during the putting stroke raises the putter head up from the ground through impact. This raising action results in the ball being struck inconsistently off the face. Sometimes the centre of the ball is struck with the centre of the putter face and then other times, the lower part of the putter face will connect with the upper part of the golf ball. This will affect the distance that you strike the ball, as putts that connect with the upper part of the golf ball will not travel as far as those struck from the centre.
A wristy putting action also affects the putter face at impact. As you flick the putter head towards the ball with your wrists, the putter face will tend to close, that is rotate left of the target line and the putter head will also be moved to the left of the target line. This will result in the ball travelling left of the target line and accuracy being lost.
To improve your strike and accuracy, rather than flicking and hinging at your wrists, try putting cross-handed and using your left arm to swing like a pendulum from your left shoulder. This will promote a much more straight back and straight through putter head movement along the target line as you lead with the left arm and this will improve your accuracy and get you holing more putts especially from 6 -10 feet, when you are out on the golf course.
If you find that you lose some feel on your distance putts with this method, then use a more traditional hold when your are further away from the hole and a cross-handed grip for improved accuracy, on your short putts.