To break 80 on a regular basis, you need to keep your drives in the short grass. Just two or three more missed fairways can mean the difference between shooting 78 or 82. To put the ball in play more consistently, it's important to develop a go-to shot off the tee—either an anti-hook ball flight to avoid trouble on the left, or an anti-slice trajectory to avoid trouble on the right. By eliminating one "bad" side of the fairway, you make the fairway that much larger and easier to hit.
To hit the anti-left ball (i.e., a fade), position the ball forward in your stance (opposite your left armpit) with your feet, knees, hips and shoulders slightly open to the target line and your shoulders fairly level. When viewed from behind, your right forearm should appear above your left, with just a trace of your left arm visible. This setup should produce the shape you want—that is, a ball that starts a few yards left of your target line and then curves gently back toward the centerline of the fairway.
To hit the anti-right ball (i.e., a draw), position the ball just forward of center in your stance, with your body slightly closed to the target line. When viewed from behind, your right shoulder should appear lower than your left, with a good chunk of your left forearm clearly visible. This setup promotes a swing direction that's more to the right, producing a ball flight that starts to the right of your target line and curves gently back to the left.
DRILL: DON'T CROSS THE LINE
Here's a great exercise to help you groove a go-to shot. At the practice range, take 10 balls and pick out a target in the distance to use as your centerline. The goal, depending on your preferred shot shape, is to start the ball left or right of the centerline and work it toward the middle of the fairway—without crossing the centerline. So if your go-to shot is a draw, you want the ball to curve from right to left without crossing into the left side of the fairway. Keep at it until you can hit seven of 10 tee shots into the correct area.