I just went back into a painting, ( a small one)....there were some areas of disharmony that were bothering me. I used a red for some dahlias and the blue in the hydrangeas wasn't sitting well with me so I decided to use 4 colors ( two cross complements). They were alizarin crimson and sap green and then orange and transparent orange and prussian blue. I feel like harmony fell into place easily which now makes me think of simply painting a scene in white and black acyrlic. I would let it dry thoroughly and then put my four colors down with white and mix up some values and start applying them to the little black and white study. I think I would have a very charming painting. Stay tuned. I'm going to do it. I'm not sure in this case I improved it but I could see the potential and definitely some areas were improved!