In 3d? I use my image (or if I do a girl, a girl's image)... as odd as this sounds, as little clothing as possible (to get proportions correct).

I then match cylinders to the basic parts, get the basic shape, then use split-polygon tool to cut in to exadurate the muscle groups (which will be massively decreased in smoothing to look realistic)

And in comes McKinley's buddy Ben's website:

https://www.poopinmymouth.com/process...er_process.htm