A friendlier name for "self publishing" that has less stigma attached. Think "indie band" or "indie filmmaker." There's bias towards authors who choose to DIY versus following the trad(itional) route.
Legitimate. An author managing the aspects of their product doesn't immediately equate to a low-quality hobby project. Established, traditionally published authors also dabble in indie publishing for personal projects, for more control and freedom, or for fun.
Fun and personally satisfying. Going independent means choosing where you need assistance and where you don't. It means always having the final say on a project, and being able to follow your own direction and not (for example) the market.
Easy money or a reliable passive income source. Depending on how you manage your budget (see below) it's possible to spend more than you will ever make in royalties. It's exceedingly common for your labor of love to be picked up by a few friends and family members, and that's it. Beware any hucksters telling you how you can make quick money by publishing low-content books especially workbooks, planners, and organizers. Without original content in them, most distributors won't even touch them now.
Fast. The actual timeline to go from first draft to finished product is faster than a trad publisher, by virtue of the fewer number of people involved. It's still not fast, though. After the final round of revisions, there's still editing, beta reading, more revisions, formatting, cover and art design, and setting up distribution. Expect it to take months of your time (on and off) at first as you find a routine and a method that works.
One person doing all the work. It can be, but it's also typical and completely acceptable to farm out some of the process to trustworthy help. Publishing is like building onto a house: you can do the work yourself, or you can hire specialists, or a general contractor to manage all the specialists, but you must do the due diligence on who is brought in, the terms of your agreement, and the costs.
Educate yourself and allow lots of time and personal forgiveness as you learn.
A guide on books and book layout. I recommend of Debbie Berne's The Design of Books [Amazon] which is a thorough walkthrough of every detail you didn't even know. It's excellent. Your library can likely get a copy for you to borrow, but you will need time to get through it. Allow yourself that time. There's a lot of terminology to pick up: trim size, gutter, bleed, frontmatter/backmatter, running head. Get a good reference and keep it handy.
Software options. The best tool is probably already on your computer or online. If you are used to Microsoft Word and have a copy, use that. Or LibreOffice if you like free (I do), or an online option like Google Docs. You do not need fancy software, though a word processor is not necessarily designed for making books. If you are used to a page-layout program and own it, go for it. You will need some software at some point, because you will need to prepare files for distribution. See the tools page for my own choices.
Learn what a scam looks like, you will encounter many. There are numerous people, especially online, who prey on indie authors. Companies using names similar to real ones who making promises about editing/cover art/marketing/social media services should always be held at a distance. Book clubs, movie producers, and television executives are not interested in you. If an offer sounds too good to be true, it is. Develop your skeptical senses and sharpen them. Always ask yourself "why does this person want to help me?" Trad publishers are paid based on sales. What is the motivation for the company that reached out to you?
Decide on your cost/speed/features triangle. This is a common thought exercise done in project management circles: "you can have it cheap, fast, or good. Pick two."
Cheap and fast: the most dangerous route in my opinion, the results will look sloppy and rushed
Fast and good is expensive: you're involving professionals and paying them to clear their calendar for your project
Good and cheap: the project will take a while, with many possible "do overs" to get right. This is the route I walk. Keeping tight control on my budget and being particular about results means it takes me a while.
Study other books, with a ruler in hand. There are a number of tiny decisions that go into a book's design, and it's good to train yourself to look at them. and the best guide I've found was looking at other books, especially recently published ones, as design and layout tastes come in and out of fashion. Know what a professional project looks like, and aim to imitate that.
What's the dimensions of the book, overall? (The trim) What size is comfortable to hold?
What are the margins used on the pages: top, bottom, outer (towards the edge of the page) and inner (the gutter, where pages meet.)
How big is the type? How many characters (letters and spaces) in a full line? Is the text justified in the center like a newspaper column, or "ragged" on the right, like a term paper?
Is there a table of contents? Any images between sections in the chapters? What page do chapters start on, the right, the left, or both?
What are the pages at the back (the backmatter): about the author, a "thanks" page? Any photos?
What does the cover look like: busy, simple, colorful, plain? What does the spine look like? The back cover? Really pay attention.
For newbies: start by publishing an ebook on Amazon to learn the process, then expand later. I know Amazon is a morally shifty territory for many people. I respect anyone who wants to opt out of Amazon on personal grounds. That said, their KDP program is very easy to set up, they have good (free) tools, and lots of documentation. You're not required to buy anything at all. The formatting tools do a decent job ("cheap and fast" at the cost of "good") and you'll be positioned to expand into other formats later, like paperbacks. Amazon had a huge reach, and from a market point of view, I would start there.
Be wary of anyone claiming to be Amazon or KDP who wants to sell you a service. It's a scam.
Get the draft done as well as possible, edit, and hand off to a trusted Alpha reader or two just to make sure the overall shape is good. Prepared questions are a good way to get targeted feedback. I try not to ask questions with a yes/no answer, but target areas of doubt I have about the piece. ("How's the pace in Chapter 3, when Prince Pomegranate is chasing the Were-Chicken through the Deep Dark Wood? How did you feel reading the passage about the Screaming Trees?")
Revise the life out of it, and get it to trusted Beta Readers with the same, or refined set of questions. I swap with fellow authors in a barter system: I'll beta you, if you beta me. I've found that handing out the work in pieces has been a good way to not overwhelm the betas, and find out early if someone is able to follow through. Not every reader will complete or even start the work. It's OK. Now is a good time to develop a thick skin.
With feedback in hand, incorporate the changes, and revise again. Listening to the text being read is my best revision tool. The ear hears things in a way that the eye skips over. It's tedious at times, and I have often put myself to sleep letting the computer read to me, but despite it being very soothing, text-to-speech is a wonderful invention. It doesn't need to be fancy software. I use the default that came with my laptop.
I use the onboard spellcheck and grammar check of my writing software (Scrivener) which does not allow AI and is simple lookup-based tools. Homophones trip me up. Be wary of online checkers that are using assistive tech to rewrite your words. See the tools page for more detail about what specific tools I'm using.
I publish ebooks first, because the formatting is simpler, and because it's possible to update the contents later for free on all my preferred platforms. And I do use a few platforms:
Draft2Digital, who distributes to many other places, including Apple
Making a typo correction for me is a grand tour of all these distributors where I have set up accounts. Previewing on each platform is always a good idea, and some platforms have specific checks to enable the title. For example, Amazon wants spelling corrected or signed off upon, and Draft2Digital has particular checks for the generated files.
Format and order print proofs. Having a print proof is essential, and worth the cost of printing and shipping. There are some experiences you cannot know until you're holding the book, especially questions of "is the gutter wide enough?" and "do I like the cover art in print?" which cannot be resolved until you're holding them. I also find new rounds of typos in the proofs that hid well in the electronic copies. It's inevitable.
I set up print on Ingram Spark as well as Amazon, and I have purchased my own ISBN to use on both platforms (allowed if the books have identical specifications: trim, paper, etc..) This is too detailed for an overview page, but remember that every fix in the paperback goes in two places, and every ebook change I make is uploaded five times. Find your problems early, it will save time later.
Click the publish button. Without marketing or some announcement, the book won't magically jump off the shelves, but there is some momentum when the title is new. Be patient, refresh your reports, and start working on the next title!