"Oil up" the painting by mixing 50% oil and turps and brushing lightly across all of nearly finished work to make paint layer more absorbent. This also makes lines of new color softer. Can then use this as the base for paint as you're Use a mixture of white, yellow ochre, and cadmium for most everything (as we are painting skin) - sometimes mixed with green (shadow) or alizarin red (bright shine, cheeks etc). End with highlights for eyes ... two dots of pure white applied with the tip of the brush handle. For a glaze ... for shadows, a green and red mixture, ultra thin. The Venetian Secret (for shadows, a mixture sold by an old lady at high cost) caught out Reynolds and other painters. Can do a black and white underpainting then cover with say a red glaze to make something that looks like red velvet.