First, don't forget to breathe.

Second, feather your brakes. That means braking lightly to reduce your speed but not completely coming to a stop. Brake with both hands evenly (front and back brakes) to avoid skidding with your rear tire or going over the front. Practice this on more gentle hills so you get comfortable with it. Brake lightly, release, brake lightly again, release, etc. to control your speed.

Third, keep your feet level -- pedals at 3:00 and 9:00.

Fourth, unpucker your butt.

Fifth, don't forget to breath.