It is important to get the correct grip pressure before each swing to keep your swing consistent. If you hold onto the club too tightly then your muscles contract and tighten, stopping the flow of your swing. Light grip pressure will allow you to relax and swing freely.

Grip Pressure
Place your hands on the club and hold the club head just below waist high.
The club head should feel heavy. If it the clubhead feels light, you are gripping way too tightly and your won’t be able to release the club face and hit a good shot.
Loosen your grip and waggle the club a few times to get the correct grip pressure.
Make sure the grip pressure is the same in each hand, not tighter in one than the other.
Keep the grip pressure the same throughout your swing.
Don’t tighten or loosen your hands at the top of your swing, especially not at impact.