Affect the mood: Blue makes the painting look cold. Warm colors like red or orange make it look inviting or pleasant.
Monochromatic: One color
Analogous: Adjacent colors
Triadic: Equally distant colors
Complimentary: Opposing colors
Desaturation (making colors look less vibrant) can make colors look more pleasing.
Foreground/Background: use of four colors that compliment each other (complimentary colors).
Use Saturation sparingly. Don’t overdo it. Best for highlighting areas of interest, or telling story.
Value: Use values of high contrast to draw attention.