How C.R.A.P is Your Site Design?
* Contrast
Elements that aren’t the same should be very different so they stand out, making them “slightly different” confuses the user into seeing a relation that doesn’t exist. Strong contrast between page elements allows the user’s eye to flow from one to another down the page instead of creating a sea of similarity that’s boring and not communicative.
* Repetition
Repeat styles down the page for a cohesive feel — if you style related elements the same way in one area, continue that trend for other areas for consistency.
* Alignment
Everything on the page needs to be visually connected to something else, nothing should be out of place or distinct from all other design elements.
* Proximity
Proximity creates related meaning: elements that are related should be grouped together, whereas separate design elements should have enough space in between to communicate they are different.
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http://www.thinkvitamin.com/features/design/how-crap-is-your-site-design