If you need a crash course in color relationships, check out this control.
Variations displays thumbnails of the current image in a color wheel array.
The main image thumbnail is in the center, surrounded by variations that are more blue, yellow, red, etc. Click on a variation and the color is added, and the thumbnails shift to reflect the new color relationships. This control is a replica of the standard Apple color picker, with a color wheel and lightness bar. You can select colors and evaluate the results in real time. Add red and see the cyan drop out, add blue and watch the yellow diminish.