Writing for the web is much like writing off the web. Good grammar, spelling and writing ability are needed in either medium. Writing online isn't necessarily any easier or more difficult than writing offline, but the medium of the computer needs to be addressed. Most people searching for information online want to be able to access what they're looking for quickly. Essential online writing skills include creating concise text, constructing well-organized short paragraphs and anticipating what your audience is looking for.
The title of your online piece is important. For example, if the title of this article was What are Some Important Writing Skills? the reader would naturally be expecting information about writing skills in general. Since this actual subject matter focuses only on online writing skills, What are Some Important Online Writing Skills? is more indicative of the content. This way, readers with the same questions can find the answers they're looking for without wasting time reading through more general content to see if what they want is there.
Most online readers don't want to spend time reading a 1000 word article when the same information could be contained in 400 words. Good online writing skills include the ability to be concise. Effective online writers understand how to analyze their topic and present complex material in a clear way. They group sentences together in logical, easy-to-read paragraphs.
Creating short paragraphs is one of the most important online writing skills. Reading print copy is often much easier on the eyes than reading material online. Each small paragraph should focus on a single idea or concept. This helps make the paragraphs into brief, digestible blocks of information that the reader can view with minimum effort.
Anticipating audience questions is important in both offline and online writing. The online writer should answer the who?, what?, where?, when?, why? and how? questions that journalists are usually taught to consider. Of course, it's impossible to anticipate every audience question, but as you develop your online writing skills you should become better at this. Having an area where readers can ask questions such as on this wiseGEEK site does help a lot!