You're struggling with accuracy off the tee. In fact, you're not just missing fairways, you're missing them by a mile.
Why It's Happening
Golfers who drive the ball erratically do so because they get lost on their downswings. It's important to think of your downswing as a sequence of events. The first third of the downswing is all about storing energy and moving the club to the proper plane. The second third of the downswing should deliver the energy through a strong, late, heavy twist. Think of a baseball player hitting a pitch he strides forward with his leg and the bat levels out "on plane." The last third involves rotating your body and hitting the ball with a square clubface. You're probably executing this sequence in reverse.
Break your downswing into three parts as follows, and practice them slowly as shown in the photos above.
1. Go to the top of your swing and stop. Your first move is to drop the club behind your back without moving your hips, shoulders or wrists.
2. As you drop the club, keep your right elbow pointing inside your right hip. This may feel extreme, but it's what allows you to set the club on plane and maintain lag.
3. Now you're ready to hit with max power on the right path. Twist your body to pull the club through. Your hips should be open at impact.
NOTE: The beauty of a proper downswing sequence is that it allows you to turn your lower body and swing your arms as fast as you can through the impact zone without worrying about hooking the ball dead left. That's where you can really amp up the speed of your downswing and hit for big distance while making sure your ball stays in the middle of the fairway.