Using color theory of cool shadows and warm highlights, I corrected this student’s painting. The student got stills with instructions of the steps, here it is simply a time-lapse. Shadows and distance are often either cool or warm, cool shadows imply a cool background. It works. I did about 12 steps, cooling up the background and shadows. For example, on the lips, I changed the blood-red shadows to violet, red+blue=violet. Then I softened the edges where there was a strong line between shadows and highlights, they always need a middle tone dividing them. Then I finished with the light using a light peach, light orange or peach is the opposite of blue — Warm light, cool shadows. I hope this is useful to you.
Michael Newberry, Idyllwild, 4/1/2020