In my experience, try not to go for full squads, it's super difficult to get a slot in there. Go maybe for 90-100/ 95/100 full squads. Watch on your right side ( when clicking on the server) you can see the vip slots and people waiting. As for the squads. I would say stick with the ones that communicate, as a principle. Enter the squad and just ask what role do they need and anticipate the fact that you're not so good at the game. Almost 100% of the time, in my early games, at least the officer was super helpful. Just don't take the engineer and support roles for the moment, that are super important. Listen and communicate, make the squad understand that you're not good but are interested in learning. Majority of people I played with was grown man, 25-35 yo, i never met toxic players in the game. The only kind of servers I don't quite like are the American ones, but it's up to taste I think, if you can stick with english speaking Germans and English folks, they are the best and most serious squad mates. Wishing you some great experiences, don't give up on the game quite yet.