This is just how I draw my humans. I use the circles on the top of the head to figure out where I want to part the characters hair. If the human is a girl, I'll tend to make the lines on the torso shorter in length. Opposite for the boys. Of course, if I'm doing a plus-size character, I'll just make a little bit of a gut (lol, I have a gut xD) I tend to make the base with a lighter, thicker brush, then add smaller details with a darker, thinner brush, then I trace over it with a thin, black brush.