One of the most common errors amateur golfers make is something called "casting" their club on the downswing, letting the club lead the arms. By the time they get to the ball they've lost all their power and the ball just kind of bounces out there.
The secret to getting rid of casting is to make sure your legs, your lower body, start your swing. You're actually pulling the club in the downswing. Then, when you reach the ball, WHAM! You uncock your wrists and smack the ball with REAL power. Casting is for fishing, not for golf.