the version I have, my very first one, is an improvement from older versions
I don’t think commercial tutorials are going to help you very much because they’re all going for publishing and getting paid. Audacity publishes process and mastering techniques that may not be right for you either, for the same reasons.
Since you’re not getting paid and you have an audience of one, you can do almost whatever you like.
Audiobooks have a “player” that can automatically go the next chapter or play the current one again. How were you planning to do this given the audience can’t see.
Things may not always go to plan. There’s two fuzzy rules: You can’t edit or change an MP3 without causing some sound damage. Audacity Projects are poorly understood, not universal, can be brittle, and don’t make good backups.
I don’t want overload my computer with too many files
That’s not a good start. How are you doing regular backups? What happens if tomorrow you push the power button and Nothing Happens? Find a way to store work. You can go on-line for this. Several Cloud companies offer serious storage for free to get you hooked.
I think at minimum you should File > Export a perfect quality WAV (Microsoft) 16-bit sound file of your Edit Master. Get a chapter as perfect as you can, make the WAV and only then make the MP3. If anything happens to the MP3, you can make a new one with exactly the same sound quality, or if you have a change or correction to the show, you can change the WAV with little or no loss of quality…and then make a new MP3. Editing an MP3 causes problems.
Very close behind that (and out of order) is making a WAV of your original live reading, mistakes and all. It’s a very New User Error to read something, edit it, correct it, master it, and export it to MP3 with no Export or Save steps in the middle. That means if anything goes wrong anywhere in the chain, you automatically have to read it again. That may not seem like a big deal now, but that will get more serious as you get further down the book.
And again, you don’t have to worry about technical standards, background noise, volume matching or any of those other problems that the publishers do.
Of course if anywhere in here you decide to read for publication, then you have to meet technical and sound quality standards. Come back by. We have processes, tools, and tricks.
Koz