I assume you're talking about heelside 360's and that you ride regular (left foot forward)?
Like Ron said, you need to initiate your rotation with the pull of the handle. Pop, pull, pass is the saying you will hear often. Pop off the wake first and pause for a split second to set your axis, pull with BOTH hands to your back hip to start your rotation, then pass the handle in the small of your back.
Don't worry about the spin as much as the handle pass. If you get that handle in tight and pass it in the small of your back then the spin will take care of itself. Be sure to cut into the wake with more of a flatter edge so that you can pop straight up and the rope won't be as tight.