When I first started writing, I followed a lot of other people's rules like in order to be worthwhile, a piece must be at least one page (i.e. 350 words long). That's hogwash. After years of writing, I have learned that a good writer cuts and cuts and cuts again, until they can succinctly get their point across. What is important is to be articulate in writing. If Twitter teaches us one thing it is that you can often get your point across in 144 characters or less!
What you say might be less important than how you say it.
This holds true, in fact, even truer for material that is published on the web.
Write because you love writing. If your goal in writing is monetary success, you may be disappointed.
Throughout history, writing hasn't been a 'get rich quick' scheme for most writers. In fact, many famous writers, such as Edgar Allan Poe, died broke and broken. If you are writing for any other reason than you absolutely love writing, you are writing for the wrong reason.