Human face drawing-face proportions

Teaching is the best way to learn, they say and this is the truth. So let's learn to draw together.
Some proportions of the head are generally common to all faces and need to be right in a portrait.
The human face has an egg form, so we draw an egg.
Before you do that, draw a grid of squares; 3 squares for the height of the egg and 2 squares for the width.

With these 6 squares we have divided the human face to it's most characteristic parts and we even have a vertical symmetry line through the center of our face drawing.

1. The hair line is 2/3 up from the brow line;
2. The brows and the top of the ears are on the same line (in many cases).
3. The nose base and the ear lobs are also at the same level.

I hate computer drawing, so one ear will do the job. We always hate things we don't master, that's human nature.

That's it, see my dummy!
(don't laugh, I know it's ugly!)

We need some more lines for the details.

Using the same overall dimensions as before for the height and width of the face (we measure them), we divide the height in 4 equal parts this time .

4. Eye level line (1) - generally is halfway from the top of the head and the chin.
The human head is 5 eyes width in front view.
If we divide the eye level line (1) in five equal parts we can see that:
- the distance between the eyes is the width of one eye (2);
- the nose width is the distance between the inside corner of the eyes or the distance between the eyes (2);
- the neck line starts from the outside corner of the eyes (3);
6.The mouth middle line is at 1/3 of the distance between the nose base and the chin (4);
- the vertical lines starting at the center of the pupils, line up with the corner of the mouth (5);

These are the main thoughts I wanted to share with whoever is interested.
Please, keep in mind that all this is just theory, just the basics, like a template.
Every human face is unique.
Still, when observing your model, while knowing the basics, you just have to discover the differences between the actual features and the "template".