I do not suggest to start learning from portrait drawings by other artists because you will be unable to develop your own language and style. Suppose you are interested in drawing from other people’s drawings. So I will make a specific post with clear recommendations on which links to take. Starting a pencil portrait Start by marking the face height and width to make it easier for you to see proportions. As to facial anatomy, you can compare how many times width is contained in a face height.
Source by jgthibodeau