Jennifer had us limit our paint colors to black, white, cadmium red and yellow ochre….plus alizarin crimson for the red onions. The 4 colors are known as the Zorn palette. Some examples of Zorn’s own use of this palette are at this link.
I am happy with how my painting came out. From a student perspective, an advantage of a limited palette is that the solution to my color problems has to be found in one of four piles of paint–cutting down on the options means less confusion for this poor student! From an artistic perspective, the result of mixing all your colors from 4 sources means everything is going to be harmonious in the end.