Then there is the practice of the eyes separate, the nose, the lips especially because they are all shadows and pigment colors of the skin.
When I watch Willowing, Suzi Blue, Milliande, or
And then, the new way I have been doing, make a copy of masters faces, and take that pencil, charcoal or marker and trace and copy on top of their eyes and noses, and lips and ears, hair and shape of face. Believe me, this is so helpful. You are not pliagerizing. I find this tracy affect is so helpful, it seems to make an imprint inn the brain on how the line qualities, shadows and shapes really make up the face. Another way is to lay tracing paper on top of the photo copy and trace and retrace. I am sure that if you practice this different way of drawing-tracing-it will help you with the placement of these things in your own drawing whether you enjoy realism, folk art style faces, cartoon, pen and ink, painting, or whatever, the whole face will be solidified in your mind.
Remember, this is just drawing exercise like when you are working out on the weight bench, and you do and redo curls, this becomes a repetitive pattern, you may go up with the weight, but you are doing the repeat over and over to build up muscle and tonality. This is what you are doing in drawing. Appreciation of art is a wonderful thing, and if you do this type of exercise, you will come to enjoy the masters and begin to see their differences in techniques.
The Mona Lisa that I have in a previous post is a good one to practice on first. I even wanted to check to see if the measurements were right and if the eyes were in the middle of the head. They are!
Have fun and if you want, just throw the tissue paper or copies away later, it is just exercise to make you a master!