Colour:

Coordinating colour effectively should be considered thoroughly. To many colours can look ghastly as well as to much pattern and can destroy a well planed display as well as losing the focal point.

The most commonly used schemes are based on six variations: Complementary, split Complementary, double Complementary, triadic, analogous, monochromatic.

Complementary: two colours which  are directly opposite each other on the colour wheel.
Split Complementary: use of three colours, one main colour and two appearing either side of it on the wheel ( yellow, orange and green)
Double Complementary: four colours. Two main plus their complementary colours.
Triadic:  Three colours that are equally spaced around the colour wheel.
Analogous: Two or more colours that are next to each other.
Monochromatic: black and white

Colours are also associated with human characteristics and emotions.

Red: Passion, love, anger
Orange: Knowledge, warmth, energy, force
Yellow: Caution, cowardice, treachery, madness
Green: Wealth, outdoors, luck. Nature, envy
Blue: Fidelity, sobriety, fear
Violet: Royalty, depression
Brown: Maturity, humanity
White: Purity, truth
Black: Death, depression, sorrow