C . R . A . P

C : (Contrast) - Two different elements, that go against each other, such as Orange and blue, black and white, red and green.. etc.

R : (Repetition) - Have a certain pattern, try to keep everything alike.

A : (Alignment) - Have everything in a certain order, so you can stay organized, otherwise your blog / poster, wont look as neat.

P : (Proximity) - Focus on one major part of your poster / image, so then you can capture the audiences attention.