Steps to take *before* running open core legacy patcher

I'm planning on running open core on my early 2013 15" Macbook pro (2.4GHz i7, 8GB RAM, GeForce GT 650M 1GB), currently on MacOS Mojave.

What things should I do beforehand to make sure everything goes smoothly and that I can fully rollback to my machine's current state if (for some reason) I decide this isn't for me?

Also.. is there a recommended OS I should target? Will Sonoma run smoothly, or should I set my sights lower?