Don't forget to consider the importance of white space on a page.

The color displayed by your computer monitor (and thus the color used in your web design) is different from "regular" printed color or photograph color.

Design/layout of a web page is similar to layout of a newspaper page or any other publishing layout.

Different text locations on the page, different use of images, different structures and colors will alter how a user expereriences a webpage and its content.

It is probably easiest to consider some pros and cons of page structure/layout by looking at some examples.