keep the rope down at your waist, as thats your center of gravity. If you have your arms straight out and the handle is high, that means youre leaning back to resist the handles pull, and youre more prone to eat it when your edge hold fluctuates.
How bout this. When the boat first pulls you up, keep teh board sideways and get a feel for sliding. You can go around the whole lake sideways if you want to. Next, practice sliding out 90* and sliding some more. Then finally, go into a slid and instead of coming out of it regular, come out switch. There you go. Surface 180.