Among Web's many peculiarities is way people read online text. It took me a lot of time (being a writer who loves to read greats like Dickens and Kafka) to realize how impatient and hurried general web reader is.
Most of web readers do not read complete sentences and paragraphs, unless they are reading a white paper or a piece of literature. They generally scan headlines, or words that grab their attention. Web readers tend to scan text online and read text offline. They typically do not read a page from start to finish on computer screen. Instead, they scan a site looking for relevant items and then print pages that contain information they seek. You need to apply a style and method to your Web documents that accommodate this type of reading.
I'm not saying there are hard and fast rules for writing for online audience, but if you take care of following guidelines, you may find yourself on comfortable side of hedge.
==> TRY TO BE CONCISE <==
As I mentioned above, an average web reader doesn't read big text streams. Unlike a printed papyrus, web is humanly limitless when it comes to seeking information. It's all on back of reader's mind that moment he or she begins to feel bored, just a few clicks are required to go somewhere else.
==> CONVERSE WITH YOUR READER <==
Write in a conversational tone whenever possible. Use lots of You 's, I's and Me's. Keep a free flow and keep throwing attention-grabbing expressions at your reader. No, it doesn't mean you create a nuisance or insult sensibilities of your reader, but try to be as formal as your subject allows.
A few months back I used to write technical tutorials for a management portal. The chief editor had hired me as a freelance columnist because of my casual but incisive style. The senior management, sadly, objected to my style and said I should tone down my humor and make tutorials sound serious and bookish. While I was writing in my style, portal was getting great response and readers were loving tutorials. When they curbed my style, popularity declined vertically, and soon, I got bored and stopped writing for them. They closed web site last week because many subscribers asked for refunds.
Lesson learnt: no matter what's field, a typical web reader does not read pedantic stuff. I don't know why, but web makes them funky.
==> WRITE IN A LINEAR FASHION <==
Try not to divide a single topic among various pages. If message is interesting and relevant, your web readers would like to read it on a single page no matter how long and bulky that page is, rather than pressing Backward and Forward buttons.
I have seen this myself, and know how irritating it is to having to go to various pages to read just one article or product description. Fine, web readers prefer shorter pages, but it doesn't mean if a paper consists of thousand pages then we should have to click thousand pages to read that paper. It's better that all content is on a single, linear, scrollable page.