Ah, the very common counter rotation problem.
A few suggestions:
1. Practice some easier runs holding the bottom sides of your jacket. It will help you get a feel for keeping your upper body in line with your lower body, as holding your jacket will restrict the movement of your upper body, especially the shoulders.
2. Always think to keep your shoulders within the width of your board. As your board moves, your shoulders should move with it, thereby keeping your torso parallel with the board.
3. Many people ride with "open" shoulders. That is, to look where they are going they turn their upper body in that direction. Using point 2 above, think to rotate your neck/head as close to 90 degrees as you can to see where you are going, leaving your shoulders parallel to the front and back edges of your board.
Hope these make sense and help.