Proper Squash Grip
The proper squash grip is very counter-intuitive. Instinct would tell you to grip the racquet with a clenched fist. The racquet has no control in the fore-aft and side-side motion with that type of grip.
The proper squash grip has two subtle features that allow you to have full control over the head of the racquet. It is extremely important to master this grip early on otherwise you will be stroking the ball incorrectly and find it very difficult to play the touch shots that pros play with ease. Furthermore your game will suffer for several months as you try and fix your grip after developing bad habits.
Adapting to the new squash grip
You may find it difficult to hold the racquet tight with the new grip. Here are some suggestions to make it easier to grip the racquet tightly
Add over-grips to increase size
Hold as tightly as possible
Focus on hitting the sweet spot in the racquet. Off-center shots really loosen your grip as they add excessive twisting forces to the racquet
Re-string racquet at a lower tension. Most factory strung racquets are strung very tightly. This makes the sweet spot very small
The above article was taken from the squashclub.org website