I've recently decided to move my current project from Node+MySQL to Firebase. With that comes a drastic change in the database schema, because Firebase is a NoSQL database. So I had to change how my database is structured. I'm still not done with it and will update this post as I progress.
First, I've written down a "perfect" structure from a data standpoint. There is always a single source of truth, so you never have to change things twice when updating. Secondly, the data has a structure that makes it very easy to read and understand without jumping to different places to see what part references what. Here is a picture of how that would look: