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 for your web design) is different from "regular" printed color or photograph color.  In other words, your 4"x6" family photo will look slightly different when displayed on a monitor.

The design/layout of a web page is similar to the layout of a newspaper page or any other publishing layout; you need to consider the location, size and appropriateness of graphics, the format and arrangement of text, different colors, etc.

Different text locations on the page, varying use of images, alternative layout structures and colors will alter how a user experiences a web page and its content.

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