Last week: the terre verte layer. Based on Cenini's stylebook (16th C "how to mix paints" incl what's poisonous and lst deets on egg tempera). We're doing it 18th C style (Hogarth era). Now we draw on the dark areas, with a Alizarin green/red mix (-> black , note "the red eats the green, and green takes forever to dry). This layer mostly turps some oil; first all turps; put "fat over lean" (but never more than half and half or it will never dry). Keep the dark layer super thin or it won't dry evenly. Okay for it to be too big as lighter colors will go on top and will fill in the edges. Also you can wipe it off. Don't overpaint or fiddle with it too much.
Next: medium skin tones. Mix yellow ochre, vermillion/cadmium red (a dab), plus white. Cheeks, go for cadmium red (oranger) or Alizarin crimson (pinker, formerly something made of beetles) in the flesh blend. Do enough mixing for your whole painting beforehand so you don't run out. To darken it, add some green. (Normally whatever is opposite on the color wheel, and not black as I would have guessed.)
Then you apply the color in blocks ... on a very light area just leave it plain for the application of the highlights (next week). Be careful not to paint wet on wet as the colors will blend in strange ways.
As a final touch you may want to take a clean, dry brush and carefully blend the edges of the color blocks to blend the contours. Keep cleaning the brush!
(This is the painting I'm aiming for - an 18th century prostitute. The spots are to cover her syphillitic pox marks.)