Step 2: Practice on the boat
Put on your gear: a padded wetsuit (this has nothing to do with temperature!), a cup if you need it, and maybe a neck brace or gloves if you like. Now, practice the motions you'll use when hanging onto the boom.
You'll start planing off on your stomach/hips, holding the boom. First, flip your body around so you're riding on your rear end. Bend your knees and angle the kneecaps towards the back of the boat, such that you're riding on your left hip. Now, use those abs to scoot your body around so that your feet face front. Brace your knees solidly together, and SLOWLY roll forward so that you transfer some weight to your feet; this is the three-point position. Transfer more weight to your feet, and let the force of the water pop you up, and you'll ride like you're sitting in a chair.
Wasn't that easy? Now, hop in the water and let's try it faster and with spray.