There should be no twisting.
Trailing hip/hand (free hand) back to corresponding hip at the finish of the turn. Hold it. Repeat.
One of the biggest differences from lower level to high level skiers is the stance on the ski. Jodi Fisher coaches skiers to square their hips to the tip of the ski so they are perpendicular to the length of the ski as when you stand with 1 foot in front of the other, you will naturally be in a hips back position. Force the trailing hip forward over your front foot by standing tall with hips perpendicular + to the ski.
Do it from the moment you get pulled out of the water. Force it in your gate and gate Glide. When you complete the pass or miss a buoy, get into that hips forward tall stance again.
Personally I try to stand on the ball of my front foot, and fall away from the handle when I pull out to drop. Great time to practice the stance.
Make sense?
youtu.be/gzdk-E5f9S0