I've been buried head first. Luckily my head was only about 4 feet down. It is very scary and you can't see anything. If you remember one thing it's that SPIT WILL ALWAYS GO DOWN. The snow may be supporting your body so evenly that you can't tell which way is up and which way is down. You don't want to dig down. So spitting a little so it can run down your face will let you know which way to dig.
Oh, to the guy that thought the only danger in the trees was running into one and thinks he can solve it by wearing a helmet, good luck with that. I have personally witnessed a skier's binding prerelease in the trees and he tee'd the tree with the small of his back. I tore ass down the mountain to notify ski patrol, but he had died instantly. Trees are fucking dangerous.