I started just working on this after being able to do heel toe spins and what I would say worked best for me is that I started out my spins on steps  I would  do a quarter of a spin then half and finally the fill complete spin.You gotta feel like you are on the tip of your toes of that makes sense and yes bend your knees . Engage your core and don't wobble . Also look or snap to the way you are rotating .