One website that I tend to avoid if at all possible is MySpace; too much of it seems to be pages composed with horribly clashing colors, backgrounds that don’t contrast well with the text, and other things that make them difficult (and annoying) to read. I would go so far as to call the typical MySpace page an excellent lesson in what not to do. What can we learn from them?
Formating your text
If you want people to to read your site (rather than hitting the back button), make it easy for them. Use 12-point (or higher) resizable text, preferably dark text on a light background. Choose one font, preferably a standard one such as Times New Roman or Arial, and stick with it. Typing in all-caps has been considered annoying since the earliest days of the Internet; use appropriate capitalization!
As mentioned, you should choose one font to use for the entire site; common page elements should also be consistent. Navigation bars, for example, should be in the same location on every page.
A number of elements are designed for attracting attention; use them sparingly. For example, this page uses bold headers to let the reader know what each paragraph will be about; randomly bolding words throughout the document would only lead to confusion! Animation in particular should be used sparingly; it should convey useful information that the reader needs to know immediately, or users will simply find it annoying. Additionally, use emphasis (bold, italics, etc) only on short phrases, and never use underlines for emphasis as users are programmed to regard underlined text as links.
Remember: making it easy to quickly scan webpages for important information makes them more useful to the user; avoid using attributes that can be distracting or make the page difficult to read. Strive for simplicity in design; don’t change how information is being presented simply for the sake of variety.