Color theory is a large field of study. In order to approach the many phenomena that occur in color, you need a firm grounding in how colors interact. Begin by getting down the order colors occurs in the spectrum.
1.) Choose a geometric shape that demonstrates symmetry. It can have bi-symmetry or radial symmetry. Use crystals or other familiar shapes like squares, triangles, snowflakes, hexagons, or triangles.
2.) Divide and fill in the areas of symmetry using radiating color spectrum. Begin with red and then orange, yellow, green, blue, and finally purple and indigo. You can work from the opposite end of the spectrum indigo all the way to the other side, red.
3.) Finally, choose a color to stain the whole work. This will change the key or the rainbow, while giving you a wide range of colors. Scratch away the overcoat to reveal the original unaltered colors.