Let's say, You're walking in the city park, then, You meet a woman, She had a long, dark, thick and shiny hair, and also, her hair looks completely unbranched.
At that time, You also find that She has a forehead that is too narrow, very thin eye brows, pug nose, and her lips were swollen. But, She has a very fresh face skin.
Can be ascertained, in Your mind You will say: "She's mediocre...", or even "She's really not beautiful...". Although You could say: "Her hair is really stunning...!", but it is very difficult for You to say: "She's beautiful face...".
From above description is already clear that the Substance of a beautiful face is about Proportionality. Apart from a presumption that, Valuing a beautiful face is something highly subjective, but, beautiful face is something that looks or highly visible.
And that meant by Proportionality is: To what extent, each of face part (forehead, nose, jawline, lips, etc) has a size or measurement which did not excessive, and, the extent to which all face parts cover each other, fused together or complement each other. Therefore, the ugliness of a face part, can be eliminated or minimized its ugliness, by another or other face part.
Then, the higher the level of its cover each other, means the higher its proportionality. That is, the higher the beauty of a face.
But it must be admitted, that the beautiful face, is strongly influenced by the proportionality of each part of its face individually, e.g: pointy nose, big eyes, very soft jaw line and others. And all of this, is the Outward and this is a God's Grace. What can be done to make the face look more beautiful, is with how to combine with a balanced, resulting in a proportional face makeup.
Actually, there are two options to make the face look beautiful, that is doing good that can be implied in a spotlight eyes and aura of the face, and an extreme way which is still a big controversy, i.e Plastic surgery.