to draw the human form you kind of break it down into boxes anyway so a cube of the head the chest the abdomen thigh knee shin ankle foot n so on so its basically keeping those rather than filling in the curves.Here's a site explaining the form the diagrams have the cubes there so basically work around those ideas.I drew a large art piece of box men years ago I found it easier not to keep the sides parallel but to taper them in
http://www.bakaneko.com/howto/figure/anatomy/index.html
