The golf club has only three components, a head, a shaft, and a grip. The shaft is the most over-rated of the three components, and the grip is typically given no consideration at all.
This is unfortunate, because the grips's size, taper, and condition will influence both how tightly the golfer has to grip the club and how he aligns his hands on the grip. Both of these factors will influence how quickly the club face rotates through the impact zone and, therefore, the golfer's ability to square the club face at impact.
Poorly sized or worn grips can lead to a loss of both power and control. As a general rule, golf clubs should be re-gripped about once a year or after every 40 rounds.
When it's time to re-grip your clubs, if you've never done so, take the time to be properly fitted. A new properly fitted grip will make the entire club feel like new.