This post will be very short because it's just a tip. It's from T.J. Tomasi's book How to Break 90, which I've quoted from before. (Remember the post on level fives?)
This is a tip on how to hit more fairways by shaping your tee shot -- specifically, it's how to be sure you hit a fade when you need a fade and a draw when you need a draw.
When you need to hit a fade, tee the ball a bit lower. This encourages you to make more of a downward stroke on the ball, which Tomasi says will also cause you to swing a bit from out-to-in. I'm guessing it would also help to tee the ball an inch or so farther back in your stance; that might help you leave the face open a little bit.
When you need to hit a draw, tee the ball a bit higher. Not so high that you go under it, he says, but a bit higher than normal. He says this will cause you to swing a bit more in-to-out. And again, I'm guessing it would help to tee the ball a bit farther forward in your stance, to give the clubface more time to close a bit before you hit the ball.
I would also advise testing this tip on the range before you take it on the course. I've heard this advice from other instructors besides Tomasi, but not every tip works for every player. Still, if it gives you a go-to shot when you need it, it's worth trying it.