Browse by "all" and block communities you don't like, after awhile you'll see trends of certain instances, go ahead and block them too.
At some point you might realize you like another instance more and want to jump ship, just do it.
There's a general vibe, but remember one of the huge downsides is it's very easy for the same people to keep making new accounts. Literally the most problematic people online who are banned everywhere "big" can easily spin up a new account on any of dozens of instances and jump into any federated comments section.
So give people a shot, but don't get hung up on "someone's wrong on the internet", a lot of people are just here to argue about anything and convincing them of anything is just a waste of time.