Love the studies!I would like to refer you to Michael Hampton's Figure Drawing: Design and Invention. Especially the Gesture drawing portion where you develop the form from "C" and "S" Shapes. You got good proportion, they are just alittle stiff. And start developing the formula of a generic body that you see in books like that one and any of Burne Hogath how to books. That allow you to understand the volume of terran of a human body an pick out distinct features from one person to another.