From an interview with Ken Kewley on Painting Perceptions website
Do not think too much. Better just to enjoy the color. Do whatever you need to do to keep excited. Play, do not work. Play is the most productive work. Opposite colors; yellow and purple, orange and blue, red and green, white and black. Buying any color that excite is not a bad idea. But a pretty color in itself is only a pretty color.
Begin with the artist love of color. This will be in the work if the mind does not get in the way. Be aware of the whole painting. Look at no color without looking at another. Every color needs to relate to every other color. Which one is darker, which lighter. Keep in the mind the colors most nameable. Keep the number of these small; yellow, orange, red, purple, blue, green, and white and black. Be aware of going towards or away from these. Think value from white to black. Yellow would be closer to white. A dark green or alizarin crimson would be closer to black. Think in this wide range.