While some folks have great success self-publishing, many do not. Because I feel protective of my editing/writing clients, I want to make sure they know some of the reasons why I am cautious about pushing them toward self-publishing.
You are investing your own money into producing a product that you will sell. I don't take that lightly. When you self-publish you (should) pay for developmental editing, copy editing, proofreading, cover design, book design, and other publishing essentials that I don't even know about.
As a creative, I've become aware that creating art and selling art are two different skill sets. Self-evident to many, but I had to learn the hard way. (Selling beautiful cards, magnets, puppets, beads, and even toilet plungers. Fer reals.)
When you publish with a traditional publisher, sales and marketing teams partner with the author to sell books. When you self-publish, you become responsible for selling every single copy of books stored in your closet, attic, basement, or trunk. (Worth considering as you decide how many copies you will buy.)
Folks who do well selling their self-published books are folks with lots of opportunities to sell in-person to audiences. These are folks who speak 30-60 times per year.
Other folks who do well selling self-published books are those who have a smart clear calculated strategy. This may include speaking gigs, facebook advertising, print advertising, publicity, inviting Amazon reviews, etc. Publishing a book and hoping it will sell, or believing it is so great that it will catch on like wildfire, is naive.
People need to learn about your book. One of the ways that happens is through advertising. I know that there are smartie geniuses out there who have mastered effective advertising--let's say...advertising on social media. They understand how to implement advertising that produces sales. If you plan to invest in advertising, don't drop the cash and hope for the best.
6. Quality Content
As a self-respecting writer and editor, I probably should have led with this one. Traditional publishers have many rounds of edits to ensure they're producing the best possible product. On the front end these include, but are not limited to, one or more rounds of developmental (or content) editing. In this early stage of editing, an editor is thinking about the reader: her felt need, her experience, her life circumstance, etc. He or she gives the writer feedback, to improve the first draft, that serves the reader.
7. Quality Experience
Further down the line in the book production process, a traditional publisher employs folks who do line editing, and several rounds of proofreading. These latter steps are critical to delivering a book to readers that is as close to error-free as it can be. A reader who finds several errors in a self-published book quickly loses confidence in the book, and may abandon it altogether.
8. Quality Design
While few of us give much thought to the aesthetic of the books we're reading, we are drawn to attractive covers before we buy a book, and we appreciate attractive interior design while we're reading it. When some element of design is "off"--style of font, size of font, space between paragraphs, etc.--our experience of the book suffers.
If you're considering self-publishing, and these don't feel like insurmountable hurdles to you, I commend you. And envy you.
Best wishes as you pursue your publishing dreams!