Personally i start by drawing a stick figure then I draw the general outline of muscles around the stick parts (for example the arms and legs change size in the middle because of bones). And a pretty similar thing for hair, speeding through a general outline of what I want.
Once that's done i just erase the stick man underneath and go over everything trying to make it look more smoother and prominent. Add random lines to make people think I spent hours on it when I really only spent like 45 minutes and that's all.
