Protect your wrists. Most snowboard injuries are to the wrists. Wear wrist guards made for snowboarding or in-line skating. Don't break your fall with your open hands. Hold your hands in closed fists while you snowboard so you won't be tempted to break your fall with an open hand. Try to roll into a fall as a paratrooper would, spreading the force of the fall over your body instead of taking all the force in one place.
So, what kind of wrist guard should you wear?
Wrist guards for snowboarders are becoming more readily available and are made for both over and inside the gloves as well as those integrated into the glove itself. What you should look for is a style and size that fits you well. Try out a few at your local snowboard shop and you'll find something that works for you.