Artists often employ a range of simple relationships to create harmony in an artwork.
Complimentary pairs, Split complementaries., Triads, Analogous and compliment, Monochromatic
Plus some are a little more complex but worth the effort
Harmonious Colour Schemes
Go through these sections one by one , using the image links in this Colour Master Index
What is Colour Anway?
Colour vs Hue
What influences colour?
Mixing colour strings of tints and shades
Mixing Colour Wheels
Mixing Convenience Colours
Colour Harmonies
Make a Harmonious Scheme selector
Printable templates for colour exercises