Don't tee it low:
As a general rule, when hitting a wood, you will want to tee the ball so that when you rest your club on the ground behind the ball, half of the ball extends above the clubface. What this allows is, like Jack said, you can hit the ball while not hitting the ground which will provide you with better contact.
When to tee it different heights:
Teeing the ball slightly lower will provide a lower shot trajectory and will generally favor a "fade" shotshape. Teeing the ball higher will generally give a higher trajectory and promote a "draw" shape.
So tee it high when:
- You are hitting with the wind to take advantage of a high ball flight
- You need to hit a draw
- You are hitting into the wind to utilize a lower trajectory
- You need to hit a fade
If you're looking to hit the dreaded straightball here, then tee it a normal height and swing away.
So hit the links, make more birdies, and No More Bogeys!