There are scores of helpful and confusing guidance videos on YouTube giving basic and advanced tips. It won’t take you long watching these videos for you to realise that audio experts are total geeks!
NB When watching videos, check the date that they were made. Audacity is regularly updated, meaning advice for one version may not apply to more recent versions. I’m using the latest version 2.4.1
The thing is, you really don’t have to comprehend what terms like compression, normalisation and noise reduction mean. All you have to do is apply these effects in the correct order to make your recording sound as it should—it won’t sound any different to you—but, it will conform to the technical requirements of ACX, which is the vetting procedure that an audiobook has to pass to be allowed onto Audible, the audiobook division of KDP.
There are several plugins that need to be added to Audacity to make things easier, including one called ACX Check which analyses your manuscript.
I’ll write a post about what I’ve done and how to apply the effects.
NB Even if your story passes the ACX Check, it still might be rejected by the Audible team for other transgressions, apparently, one can wait several weeks for a response.