Suggestions for writing for the web
Keep it short
People tend to read a lot less on a webpage than in a book or a newspaper. You need to keep what you write short enough so that things aren't missed by the reader. It depends on your audience though. Younger people are inclined to read less and older people are willing to read more. Anything that is specifically targeted at a group of people will be more likely to be read for longer by the intended audience than by others.
Use headings
Headings help people to see what the main points of what you write are and this makes it easy for them to skip to the sections that interest them. Headings also summarize the main points of what you are writing so that the reader doesn't have to read the whole thing to understand a bit of what it is about.
Use lists
If you need to list something then you should rather use a bulleted or ordered list than a list separated by commas in the middle of a paragraph. It makes it easier for the reader to find important lists of items and it makes them stand out.
Use bold text for important points
Any very important points that you want to make should be made bold. This will help the reader find all the important things to read and will allow them to skip over all the useless filler if they don't want to read everything.
Keep the most important information near the top
Your readers are most likely to read things that are closer to the top of the page because they lose interest as they go down. This also applies to paragraphs. The most important point of a paragraph should be put in the first sentence. Readers like to skim read by reading the first line of a paragraph to see what the rest of the paragraph is about.
Don't write like Shakespeare
Trying to show off your ability to speak in complicated English will scare people away. Hardly anyone is willing to try to read something that is hard to understand. They can get the same information that is more simply written from another site and they won't be bothered to stick around and read yours.
Follow what Jakob Nielsen has to say
Jakob Nielsen's website is an excellent resource for ideas on how to write for the web. He has also written some books that are very good. He is considered the number one expert on website usability.