Eric Reiss offers 20 tips on writing for the web that will help you make sure your information is clear, objective, and structured to quickly get to the point. For example:
Take a critical look at what you’ve written. I often discover that if I cut out my first paragraph, I will improve the text 100%. On the web, visitors want you to get to the point. They’re not on your site to admire your fine writing.
(Via Future Changes)