The light we as photographers try to put on a face might be over thought. Learn to feel what the right light is for your subject and that should be the light you use. The magic comes from a single source of light, with sometimes, a soft reflection of it from other sources. When you see perfect light on a subject, you will begin to see perfect pictures as well.
Then the rub…always know light is not the star – you and the subject are. Light is only the currency that is used to make the image. The image always resides in you and the subject.