Most people grip the golf club way too tightly. This keeps the head from squaring up when it hits the ball and results in shots that are more likely to shank to either side. Too string a grip also results in less swing power and shorter distance on your shots.

The correct grip strength is actually much lighter than most people would imagine. To get the correct feel for the grip, take a tube of toothpaste and remove the cap. Grip it with as you would a golf club and start squeezing. The proper grip strength is right before the toothpaste starts coming out of the tube.