Tee the ball higher than the middle of the face.
It doesn't take a Ph.D. from Stanford to notice that drivers have gotten bigger--and taller--during the past decade. However, many players haven't changed the height they tee up the ball when hitting that big driver, so they aren't getting the optimum launch.
It makes sense that a taller clubface would require you to tee the ball higher to hit it in the middle of that clubface, right? That's true, but to really get the most distance, you actually have to tee it higher than the middle of the clubface--for two reasons. First, you're hitting the ball on the upswing, so the club will be coming off the ground, not skimming it. Second, you want to hit the ball just above the true middle of the face to launch it high without too much backspin.
The rule I like to use for a driver is that two-thirds of the ball should be showing above the crown when you tee it up. And that's at minimum. You could even get away with teeing it up so the ball is completely above the face. Just make sure you're using a regulation-length tee. The U.S. Golf Association has limited tees to a maximum height of four inches. I haven't seen a driver yet that is tall enough to make a four-inch tee obsolete, but you never know.