Alignment - items on the page are lined up with each other. Lack of alignment is the most prevalent problem on the web. Items can be aligned left, right, centered. Choose one and use it for the entire page. Do not mix alignments.
Horizontal alignment is just as important as vertical alignment.
Steer away from centering everything. It's weak and because it is so symmetrical and balanced, it's very calm and formal. Turn the borders off and use aligned text to create visual separation necessary for columns. Proximity - refers to the relationships that items develop when they are close together, in close proximity. When two items are close, they appear to have a relationship, to belong together.