Keep your weight distributed evenly throughout your feet, pressure on the front of your boots, and keep your chest and head up. When you take off, pop like a motherfucker.
Good way to learn how to hit jumps; just rip around the hill and send it off everything, but try to land well. Hit side booters, little wind lips, whatever. Just make sure you can land well off all kinds of stuff, and try to go as big as you can. Seems silly but the more you practice popping and landing off crappy features, the better it will feel and the more confidence you'll have when you start hitting regular jumps, which are shaped and maintained so that they're nice to hit.