The important part to remember about self-publishing is the word "self." You do everything yourself, or pay for someone to do it for you. Even before your first copy is available, you do the editing yourself. You do the layout yourself. Cover design - yourself. All the technical requirements for creating the files that make the book - yep, that's done by yourself as well. Sometimes it's easy to outsource these, which is fine, but they need to be done and they cannot be taken lightly.
Just as a side-note, the most common route for self-publishing is Amazon's KDP. It is a full-service suite for publishing where you can buy features that are normally outsourced, or if you prefer, you can publish for free without their premium services. More importantly, any book published through KDP is examined by other retailers, who may list the book in their catalog as well.
So, let's say you finally get into print. Excellent. Now what? Well, self-publishing also means that you wear a bunch of other hats, and the weirdest one you will wear is public relations - you are your own PR agent, making sure the world knows about your new book. This is a job in itself, and if you want to sell copies to people other than your Aunt Pearl, you need to promote yourself long before your book is published.
Self-promotion is more than just an Instagram post that you've published a book. Social media is very important, but it's not the only route. You should be on several social media sites talking about your upcoming publication and asking about how to promote your work. You should be looking into ways to get buzz stirring - local libraries are great routes for writer forums, and you will want to make sure you find out about whether you can have a presentation as a local author and sell some autographed books. (Yes, you should have a stock of books you are willing to sell at a moment's notice. Consider them the biggest business cards you can carry.) A publisher would normally help you with these things. Self-publishing means you do all this yourself.
Scared yet? Don't be. Anything worth doing is worth putting forward the effort. If you're a little nervous, great - that means you're taking it seriously. Look into it as an option. It might be a great way to get the ball rolling and stir up some buzz for future publications. And believe me, nothing quite matches the feeling of holding a book and seeing your name on the cover. It is the validation that nothing else can ever match.
Aunt Pearl will be proud.