I'm not a portrait artist, but one of the projects I set in my Painting I class is to paint a portrait from a photograph. I teach students a very-simple-to-remember "recipe" using approximately seven parts white (I prefer flake white because it's warmer), one part yellow ochre, and a pinch of cadmium red light (about the equivalent to two tenths of one part).
For shadows I encourage them to experiment, but using more yellow ochre and cadmium red will gradually darken the skin tones. For more drastic and darker shadows I suggest adding burnt sienna and/or burnt umber and even a little alizarin crimson. For darker skin tones I usually suggest using burnt and/or raw sienna (depending on how "red" the color of the skin might be) and green (the green usually suggested is viridian, but, again, I encourage experimenting until they find something they like). I do encourage strong value contrasts for a more dramatic effect.
Sometimes the shadows in photographs are grayer and for that I suggest they mix a pure purple (I actually refer to it as "grape") with a yellow (yellow ochre works here, too) to get a neutralized different sort of gray that can be successfully mixed into their flesh tones. The colors I teach them to mix for "grape" are alizarin crimson and ultramarine blue.
Tip from: Jim Meaders
As a portrait oil artist for more than 20 years, I was thinking about what would be the most valuable tip I could give someone who was doing a portrait for the first time. I deducted, of course, that skin colors are important, and many people when trying to paint a portrait may use the one tube of 'flesh color' that some paint manufacturers produce. But, in a face, there are many, many various tones of flesh colors.
Here is my best 'recipe' for flesh tone colors:
1. Titanium white
2. Cadmium Red Light
3. Cadmium Yellow Medium
4. Yellow Ochre
5. Burnt Sienna
6. Burnt Umber
7. Ultramarine Blue.
For light flesh tones use colors 1, 2, 3, and 5.
For medium flesh tones use 2, 3, 4 and 5.
For dark flesh tones use 2, 5, 6 and 7.
Tip from: Monique Simoneau
Don't waste your money buying ready-made, so-called flesh tints. Simply mix some white, yellow or golden ocher, and a strong red such as cadmium red. Keep the amount of red to a minimum to avoid going too pinkish. For darker tones, add some Payne's grey.
Tip from: Jo.