There's more than one way to hit the ball long. Just look at the swings of long hitters like Tiger Woods, John Daly and Fred Couples. Each is different and each serves its purpose well. However, to hit your longest, most powerful drives, three elements must be present: You must fully release the club, swing with an even tempo and remain in balance.
A great way to practice all three and to hit longer drives is to practice with a wedge. That's right, a wedge. Assume your normal grip and address position but, before taking the club back, lift your right thumb (for right-handers) off of the grip. Hit balls, focusing on making smooth, rhythmic swings. With your thumb off of the grip, your wrists will release naturally and fully through the ball. Hold your finish position for a three count after each swing. If you're able to assume and hold a picture-perfect finish, you can rest assured that you're in balance and swinging with a nice, even tempo.
Long-drive competitor Darryl Anderson captured the 1994 RE/MAX National Long Drive Championship.