Since my recent avatar picture is the turn, I figure I'd might as well share my 2 cents on the subject.
Coming into the wall your head and torso should attempt to line up with a 45 degree angle to the back wall and bottom of the pool. (Keeping hips, legs, and feet close to the surface) This deeper upper-body position makes it much easier to get the hips and feet "spinning" over the top. As soon as the hips have crossed the "tipping" point, then your head and torso should go immediately in the opposite direction (closer to the surface) while your feet land on the wall in a semi-extended state. (See the picture)
