Below are tips from my experience with self-publishing.
According to various sources 30 - 34% of the ebooks sold on Amazon are written by self-publishing authors. Amazon adds approximately 4 million books to its site annually. That's a lot of self-published books.
Amazon offers a free publishing platform that permits authors to upload their manuscripts and covers to Amazon which publishes the books as ebooks and physical paperbacks/hardcovers on Amazon. The publishing platform, Kindle Direct Publishing (KDP) is separate from the Amazon shopping site but can be accessed with one's Amazon shopping account ID after creating an account on www.KDP.Amazon.com.
In theory, an author can upload their manuscript and book cover through KDP. Many authors do that but the manuscript and cover must be on files formatted to KDP standards. For me, the word format is a red flag because I know if an error is possible, I'll make it. So I worked with a group, Word2Kindle which for a fee, formats and uploads manuscripts and covers to KDP. For a fee W2K offers other services including editing, cover design and creates advertising files featuring the book that can be added to webpages, facebook pages or any other site.
I found two online resources that helped me learn about self-publishing, the Author Learning Center (www.authorlearningcenter.com) and Keri-Rae Barnum at New Shelves Books (https://newshelves.com). The ALC offers webinars on self-publishing and promoting books. For a nominal annual membership fee, writers can sign-up for webinars and get access to the ALC library of past webinars.
I first learned about Keri-Rae Barnum through her ALC webinar on the importance of understanding the role of "Keywords" and Search Engine Optimization (SEO) for anyone who is publishing their book on Amazon. Ms. Barnum also offers a free Zoom webinar at 10 AM (Eastern Time) every Friday called Free Advice Fridays (FAF) during which she answers questions from participants about self-publishing and reviews changes in the publishing industry and Amazon's practices that may affect anyone self-publishing. She also offers a free library of all her FAF sessions on her searchable YouTube channel. She covers every topic imaginable on self-publishing.
I used Microsoft Word for writing my manuscripts which allowed me to easily send copies to anyone but more importantly offers a feature called Immersive Reader under Views that reads your word document aloud. I found this very helpful for editing the manuscript. Set the text size to minimum for faster readings.
One of my goals has been to get my books into libraries a topic that comes up frequently on FAF and is also covered in Ms. Barnum's YouTube library. Libraries do not purchase books for their catalog from retail vendors like Amazon but only from business-to-business vendors including IngramSparks which offers a variety of services similar to Word2Kindle but I was only interested in making my ebooks available to libraries. This is done through their platform Draft2Digital which requires formatted files for the manuscript and cover which are uploaded through D2D. I asked Word2Kindle to send me copies of the formatted files for Amazon which I easily uploaded myself for free to Draft2Digital. What I did not realize about uploading my books to IngramSparks through D2D is that IngramSparks distributes ebooks not only to libraries but many other book sellers including Apple Books and Barnes & Noble. You can choose these and other sellers while registering your book with IngramSparks. During this process you also see what percentage of the book's cost goes to the author. IngramSparks turned out to be a valuable resource for getting my ebooks into retail stores.
A website and Facebook page are important tools for promoting books and events. There are many sites for building your own website. I tried out several for free and chose Hostinger because I found its tools easy to use and it allowed me to create and register my domain name plus add an email address for the site. Everyone suggested creating a Facebook business page separate from my personal account. Hostinger allowed me to link the two and offers the option to link other social media accounts to the website.
Congratulations - You've published your book on Amazon and have joined the other 4 million new titles added annually. You might want to consider how to promote and market your book. ALC and New Shelves Books offer lots of webinars on these topics plus advertising. One thing everyone stresses is that promoting your book should begin months before the book's release. Promoting, marketing and advertising are all topics that should be researched in advance of publishing if possible. In my case, I didn't think about these things until after the books were published so I'm playing catch-up. But it'll all work out. It's been lots of fun! Hope you find these tips helpful.