I've been running one of the largest writing communities online for many years now, and the first thing I always tell writers when they say they want to self-publish, is that after the novel is done, then your work is only just beginning.

Marketing is just as, if not maybe even more, important than actually completing a saleable novel. Unfortunately like many of us, writers are usually only interested in their specialty--writing--and so find marketing difficult and tiresome. Lots of great novels have languished due to an author's disinterest in marketing. Likewise lots of mediocre or bad novels have succeeded thanks to clever and diligent marketing.

This is one of the many reasons why self-publishing will never overthrow the big publishing houses, like so many people predicted a decade ago. The fact is that going from manuscript to financial success involves lots of different skills that most authors just haven't been trained for, like cover design, copyediting, printing, and marketing. In the traditional arrangement, publishing houses do all of that non-writerly work for the author in exchange for a profit share.

One can self-publish and keep all the profits, but most writers don't understand that that also means you must also be a pro-level cover artist, copyeditor, printing expert, and marketer (or have the money to hire them yourself).

(There are other good reasons why publishing houses aren't going away anytime soon despite technologist's frenzied predictions, this is just one of them.)