Agree with Marco and Horton, however, I find it best not to LOOK at anything while sliding the turn, just keep the head level and concentrate on the FEEL of the MOVE itself. Keep shoulders level and let the head move WITH the shoulders concentrating not to rotate and do not let the back counter-rotated arm move faster than the ski.
Ideally, the rear hand, handle, and outside hip all meet together at the same time. Then its time to drop and leverage against the boat with these three locked together.
Key is not to look cross course or at the next buoy because this will result in dropping the inside shoulder, creating rotation, and you will grab more angle than you can sustain.
GOODE LUCK, ED