After trying numerous color combination's I have come up with a simple color palette that gives me the full spectrum of color using only 3 tubes of paint; Pyrrole Red, Cadmium Lemon, and Pthalo Blue. All these colors are lightfast and mix well together. I am able to mix virtually any color from this combination. The dark purple you get from Pthalo Blue and Pyrrole Red makes a great substitute for black. I recommend using a limited palette to color mixing and make color harmony easier to achieve.