Taima's breakdown of the boxes is a huge thing to focus on. I think of them like "anchors", solid pieces that move in relation to each other. A circle for the head, a core line Spine, a box for the Ribs, and a triangular Pelvis.
You dont need to understand their EXACT shape, but knowing how to shape them out will help you be able to get the core of a pose down very easily, and then can use ball-sticks to work on filling out the limbs
The key to drawing bodies is to understand what bends and what doesn't, and using that to break up the body nice and easy blocks that all fit together.
