Organization & proximity: placing like items together in a graphic with appropriate spacing (not too much, not too little)
Hierarchy: the order in which the information is presented (logically, in order of importance)
Example:
http://payroll.intuit.com/sbweb_payroll/category/understanding_w2/images...
Today is Tax day! Nothing says "poor design" like a form that most people have to pay someone to complete for them!