Here is a couple of things on execution.
- Shadow: use a big soft light to avoid sharp shadows. After experimenting with a soft box, I opted for a shoot through umbrella. Align the light so that you get a soft nose shadow on the dark side.
- Eyes: get both of them. If the shadowed side of the face does not show a good amount of pupil and white, then move the umbrella forward.
- Glasses: a subject with glasses can be challenging. If you place the light too far to the front or too low then your light will reflect in the lenses and muck up your sharp eyes. If the light is too far to the side then you will get a cyclops. This needs a balance, so find a good compromise.
- Face: align it to get good lines. There is nothing natural about a portrait pose, and comfort is not a great concern -- it just has to look good. Look straight at the camera to avoid a 'bad side', a puffy cheek, or jaw line issues. Remember to move the head slightly forward, relative to the rest of the body, to avoid a double chin and to improve the jawline. An exception case might be with a very slender face, where other creative options would work even better.
- Drama: a portrait is not a LinkedIn headshot, so it's not just about an elegant face and propriety. Be memorable, be vulnerable, expose something of your private life, or generally cause gawking and wonder. Add more clothes, less clothes, props, posture or anything that works.