Text Matters: Writing for the web: an overview

Language: clear and simple

Because reading text on screen is more difficult than reading printed text, you need to convey your information as clearly and concisely as possible.

Don't use five words where one would do and try to avoid using long, complex sentences.
Do not use footnotes or endnotes; these could force the reader to scroll up and down a page. Say what you need to in one place.
Use contents lists, headings and subheadings that are meaningful; can you tell what a page is about from its heading? This will make it easier for users to decide what pages or parts of pages they want to read, without having to read through everything.