make sure your feet are shoulder width apart, stay center in your weight, set your shoulders. When you reach the lip, turn your hips, shoulders and head. You will spin the rotation doing this. The next part is spotting your lading. For my first 3s of the season, it took awhile for me to get that haha. You don't need ot look with your head the entire way. Just when you get to 360, look down. There is your landing.
Some things that may happen include spinning too far, not spotting your landing and going to flat, and going into the jump either too fast or too slow. You only need enough speed to clear the jump, don't go too fast.
Hope that helps. Let us know how it goes.