Many questions from tags get answers stating something like "have a Session 0", which means "sit down and tell each other what do you expect from the game". Some of them mention the Same Page Tool. But what exactly should I do during that "Session 0"? What should be my plan? What should I not do?

I need advice applying to Pathfinder games in groups of mixed experienced levels, from "I have read the PHB yesterday" to "I have tried D&D the same year it was released", because while the latter know their desires, the former likely don't.

As I can get it from the questions here, lots of the problems may arise, and I would like to shut them down in advance.