In General:
It is easy to think that it would be good to do something "special" with makeup for your headshots. My advice, when it comes to headshots, is to be authentic. Authenticity is what builds trust with the viewer.
⠀
With that in mind, I would use the approach of doing your makeup as you would when going to the office. A natural look will add a level of credibility and will be more effective than trying to look like a model.
⠀
Skin:
Use a liquid foundation instead of powder. This will give a more hydrated look as opposed to having your skin look dry.
⠀
Avoid makeup that has an SPF in it. This usually reflects light too much. For the same reason, stay away from "translucent" makeup. The dewey look might be great for other situations but, in a headshot, it is going to reflect too much light and create hot spots. These are not easy to retouch with a result that looks natural.
⠀
Keep the color close to the color of your neck so that it blends with the rest of your skin color. Makeup looks very obvious when the face is one color and the neck is another.
⠀
Eyes:
Keeping in mind that a natural look is better for headshots, it is better to maintain a light approach to eye makeup. Avoid the smokey look or intense colors.
⠀
Stay away from heavy under eyeliner. If you can, stay away from using liner under the eyes altogether. It really stands out in a headshot but, if you choose to use it under the eyes, keep it light.
⠀
Lips:
Avoid using lip gloss as it reflects too much light and creates unflattering highlights on the lips.
⠀
Also, keep the lipstick within the outline of the lips. Going beyond the lips' edge to make them appear fuller sticks out like a sore thumb in headshots. This doesn't have a natural, clean look, which I believe is one of the most effective traits of a good headshot.
⠀
Makeup Artists:
If you are going to use a makeup artist, check to see if they have experience in doing makeup for photography. As you can see by what I have stated above, there is a difference between makeup for looking glamorous as opposed to makeup for a good headshot.