Rules for web design

Your web site should be easy to read
The most important rule in web design is that your web site should be easy to read. What does this mean? You should choose your text and background colors very carefully. You don't want to use backgrounds that obscure your text or use colors that are hard to read. Dark-colored text on a light-colored background is easier to read than light-colored text on a dark-colored background.

Your web site should be easy to navigate
All of your hyperlinks should be clear to your visitors. Graphic images, such as buttons or tabs, should be clearly labeled and easy to read. Your web graphic designer should select the colors, backgrounds, textures, and special effects on your web graphics very carefully. It is more important that your navigational buttons and tabs be easy to read and understand than to have "flashy" effects.

Your web page layout and design should be consistent throughout the site
Just as in any document formatted on a word processor or as in any brochure, newsletter, or newspaper formatted in a desktop publishing program, all graphic images and elements, typefaces, headings, and footers should remain consistent throughout your web site. Consistency and coherence in any document, whether it be a report or a set of web pages, project a professional image.

Everybody should be able to access your site
If people cant see your website because the text is to small, or if they aren't able to operate a mouse and are using some other form of software that relys on accesskeys and your website doesnt have them, how are they going to navigate your website?

Just my little contribution...

I agree
Usability should take priority over fancy graphics for the majority of sites and accessibility standards should be followed wherever possible.
I would also suggest a good search facility is important for all but the smallest sites

usability and content. the two most important factors of a site. asimple design but with good content and great usability is always preferred over the site with just one of them

Thats why google made it so far, usability and a simple design. Function is what its about.

[FONT='Times New Roman','serif']It’s like basics of web design. There should be well defined links. The things needs to be obvious and should communicate the message along with theme. Clear text does not confuse visitors as they are aware of what they are doing along with the paths.[/FONT]

usability and content which makes users stay longer and give you lower bounce rates.

UI must be simple and user friendly.

A good simple interface, careful selection of colors, fonts and text sizes. Along with a clean implementation and very careful image selection are all very important in designing a site.

Don't forget the content - it must be relevant and readable in another way. Careful with long sentences and polysyllabics!