Overall I like your Harley Quinn drawing, but there are some proportion issues that bother me.
Both of her hands, but especially the one by her feet, are really tiny, and her red arm is really thin. Her leg that's closer to the viewer, on the other hand, is quite a bit too big; the lower leg alone (excluding the foot) is as long as other lower leg (with the foot). Overall, the front leg is about a head length longer than her other leg.
By the way, I like that you included movement in the pose, but spines don't bend at a 90 degree angle.