Mapping Out A Face is designed to help you with the first and most important step in drawing a realistic likeness of a face (a portrait), that is getting the features in the right relationship and getting the proportions of the parts of the face correct on the page.

All too often those new to portrait drawing imagine that a portrait consists of putting eyes, nose and mouth in the right places, but these elements are not in reality separate from each other but are simply high points of a single structure. This single structure is like a 3  dimensional "land mass" that each face has and which makes it distinctive from other faces.

Looking at the human face in this way, and learning  how to make a "map" of it, is vital to creating a drawing that actually looks like the person being drawn. This process has to come before toning and details, but once you 'get' this approach, your ability to draw a realistic portrait will grow in leaps and bounds!

More info - https://www.skillshare.com/classes/Portrait-Drawing-Fundamentals-Made-Simple-How-to-Draw-Realistic-Heads-Faces/2095085492