The only time you should hit a 3-wood off the fairway is when you can reach the green. One of the biggest strategy mistakes I see from amateurs is grabbing the 3-wood whenever they're too far from the green to get there. It just doesn't make sense. The 3-wood is the hardest club to hit off the fairway, so using it to just advance the ball is crazy. Hit your 5-wood instead. The 5-wood has more loft, so it's easier to get the ball in the air. And unless you're a powerful swinger, you probably hit it as far as your 3-wood anyway, certainly far enough to knock your next shot on the green.
WHERE TO PLAY THE BALL
With fairway woods, set up with the ball a few inches inside your front heel. Many golfers play it way up and try to sweep it. No good. You want to hit down on it, like an iron. With the ball in the right place, your shoulders will tilt back and your hands will hang below your left ear (right, top). You shouldn't have to stretch to reach the ball.
GET OFF YOUR RIGHT FOOT
The most common swing fault with fairway woods is getting stuck on the back foot and swinging up on the ball. That's why you see a lot of thin contact, even topped shots. Your first move down from the top should be shifting off your back foot (right, bottom). That moves the low point of the swing forward so you hit down on the ball and catch it solid.
Butch Harmon, a Golf Digest Teaching Professional, runs the Butch Harmon School of Golf, at Rio Secco Golf Club in Henderson, Nev.