I've been writing professionally since 1969. I've had books published by a big-name publisher (Doubleday) and by a small, long-gone publisher—but most of my 40-plus books have been published by my own Silver Sands Books.
When others published my books all I had to do was write. I much prefer the control, speed and income when I publish my own books, but I have to do much more work.
Here's some of what's involved:
1. Have at least one book idea.
2. Unless you are using a publishing services company such as Xlibris or Outskirts Press and are willing to have its name on your books, pick a name for your own publishing enterprise. Think of several acceptable names and do some research so you can select one that’s not already being used by another company in publishing or a related field. Even if you now think you will publish in just one genre, pick a name that won't limit the kinds of books you will publish. You may think you'll publish books only about car repair, ballet or vegetable-growing, but a too-specific name will hurt your chances to expand if you change your mind later. It may be tough to market a sci-fi book if your company name is "Ballerina Books" and your logo is a tutu or ballet slippers.
3. Register the name in the local government office that registers names, often the town clerk's office. You will get an “assumed name” certificate, “fictitious name” certificate, or a “DBA” (Doing Business As) certificate. It probably will cost just a few bucks. You may be required to advertise the business name in a local newspaper.
4. Get whatever licenses or permits that your state or municipality requires.
5. Open a business checking account under the business name.
6. Get business cards.
7. Set up a website.
8. Set up a businesslike email address, don't use your personal Gmail or Yahoo email account.
9. Write the first book.
10. Have the book copyedited and, if necessary, get more extensive editing.
11. Have the book read by several laypeople and, if the subject is in a specialized or technical field, by one or more experts on the subject.
12. Make the suggested changes.
13. Either gather the necessary photos, graphs and illustrations or have custom artwork made.
14. Either design the interior yourself or hire a pro to do it.
15. Either design the covers and spine yourself or hire a pro to do them. (You should probably hire a pro.)
16. Show several cover alternatives to people whose judgment you respect. Strive to stimulate thought and dialog—not merely “I like it,” “I hate it,” “OK,” “wow” or “hmmm.”
17. Put your manuscript into book-like format, using either Microsoft Word or a more sophisticated program.
18. Insert the artwork in the proper positions.
19. Read, read, read, and have others read, read, read—on the screen in multiple formats and on printed papers.
20. Establish an account with Lightning Source, IngramSpark, Amazon's KDP (which absorbed CreateSpace) or several of them so they will print and distribute your book—or use a publishing service if you want to do less work and are willing to have less control and make less money. If you plan to publish only ebooks you can do everything yourself with Amazon's KDP system (Kindle only). If you want broad distribution, I recommend eBookIt.
21. Promote, promote, promote. Let lots of potential readers know that your book exists and convince them to buy. Promotion includes news releases, book reviews, comments on blogs and websites, email signatures, your own websites and blogs, social networks including Facebook and LinkedIn, distributing business cards, mailing out letters and post cards, signing autographs at bookstore sessions, and whatever else you can think of. Below I have inserted a picture of one of my recent books, Do As I Say, Not As I Did. Here's a link. This is a form of promotion. If you're an author who wants to make money, you have to promote your books. If you are bashful, you may starve.