The best way to tell you is to show you, so here is my friend the former General Obi-Wan Kenobi to help:
Skin color (pretty much any human skin color in almost any ordinary lighting) is
- lower saturation yellow at its brightest
- higher saturation orange/red in the middle
- lower saturation brown/gray at its darkest
That’s really it?
Skin gets pinker and redder where there are more blood vessels closer to the surface (lips, ears, nostrils, eyelids) and grayer and bluer where there are less, like your jaw.
But even if the person has very dark skin, and they’re standing in some blue light, it’s still pretty likely you’re going to find the same pattern of [low sat, high sat, low sat] or [yellow, orange, gray].
If you’re drawing by observation, and you get stuck, it’s a way to check yourself.
I hope this helps. D: