Well if you want to be in a S2 team you should get S2 first.
But there are, of course, also many nice demo teams, especially NOS is afaik racing mostly in the GTI on Blackwood, and they are not the slowest
The best way to join a team is driving with them online. If you meet some nice racers, just ask them where they are regularly. If they have their own server, it's easy