Hips should generally be centered front/back. (as you get better, all rules can be broken at times) Turns are initiated using flexion (bending) of the low body and shifting the knees and hips. Knees toward the front of the board a bit on heelside and toward the inside on toeside. Hips thrust forward (in relation to your body, a humping position) on toeside and backward (like you are taking a dump) on heelside. Hump and dump, hump and dump.
It is good to lead with your hips, but it sounds like you are rotating your upper body and leading with your shoulders. If you can have someone take a video of you, we can give you a lot more specific advice.
It is true that women often shift there hips forward on the board. This usually means you have your back leg straight. It works fine on the bunny hill, but as soon as you ride through the choppy steeper stuff you're going to get bounced all over the place. In order to really ride well, you have to bend your knees and ride dynamically, absorbing the terrain and actively engaging your edges.
If you get to the bottom and don't feel like your legs are getting a serious work out, you are doing it wrong.
Lessons with a good instructor are usually worthwhile. Snowolf has some great videos as well.
Last edited by baldylox; 02-10-2012 at 08:33 AM.