Hi Marc! Thanks for your nice comments.
Well.., about my "blacks", I used a intermediate colour, no pure black.
Base colours I used is all the game of greys making myself, leave Pure Black for shadows.
The base colours make it to add at black, orange, magenta, pinks, red or blue result a game of greys very rich.
For the lights I added more orange or magenta, etc. and for the highlights I used beige red or flesh tones, white just in any cases.
The shadows are in Pure black, anytime I used oils, only for shadows.
Try it. regards. Matito.