Depending on size until you get stable, 17 - 18mph would be fine. Start by getting stable on the ski and then work on simple things like jumping one wake at a time (jump from in to out, then out to in off each wake). Don't start with tricks right away. Get comfortable with riding the ski and getting balanced. You have to learn how to use the edges to move around instead of a fin. Also learn to ride the ski with more weight on the front foot and shoulders over the front foot, not leaning back like on a slalom ski. The most important thing is to have fun.