When painting a portrait of a face in proportion, it is important to do all of the following, except “To keep the size of the ear the same as the size of the eye.”
While the other points help maintain facial proportions, the size of the ear and eye can vary significantly from person to person and do not have to be the same. The other proportions (corners of the mouth lining up with the centers of the eyes, the width of the nose being about the same as the width of the eye, and the location of the eyes being in the general center of the head) are all consistent rules in portraiture.