The red/blue lines I add are for me to get the shape, muscles and look of the body. Nothing much to explain.Notice For the record; I'm studying human anatomy through observing myself, my family members and 2 books I have on anatomy (Leonardo Collection)
When I'm all set to draw, I am drawing according to my style, not to say that anything wrong there is what defines my style, but there are some proportions (face and head) that slightly differ due to my preference for the look of my characters.
Still, I appreciate all the point outs on mistakes I'm doing, will be good to know and easier to memorize for my own personal knowledge ^^
Head-Neck: For more tutorials, anatomical studies and step-by-steps, support at patreon page. Thanks