Eye theory and colour theory.

In the west the eye follows the same path on a image. They start slightly to the right of the centre, then to the top to the right bottom of the page. This makes a Z shape. I have used this idea on the adverts I have made.

Colour theory is also something I looked into.
A massive post about colour and its relationship, http://www.jiscdigitalmedia.ac.uk/stillimages/advice/colour-theory-understanding-and-modelling-colour
http://en.wikipedia.org/wiki/Color_wheel Wikipedia post on colour wheels.

Red is the color of fire and blood, so it is associated with energy, war, danger, strength, power, determination as well as passion, desire, and love.
Orange combines the energy of red and the happiness of yellow. It is associated with joy, sunshine, and the tropics. Orange represents enthusiasm, fascination, happiness, creativity, determination, attraction, success, encouragement, and stimulation.
Blue is the color of the sky and sea. It is often associated with depth and stability. It symbolizes trust, loyalty, wisdom, confidence, intelligence, faith, truth, and heaven.
Yellow is the color of sunshine. It's associated with joy, happiness, intellect, and energy.
Green is the color of nature. It symbolizes growth, harmony, freshness, and fertility. Green has strong emotional correspondence with safety. Dark green is also commonly associated with money. 
White is associated with light, goodness, innocence, purity, and virginity. It is considered to be the color of perfection.
Black is associated with power, elegance, formality, death, evil, and mystery.