In all honesty, I wouldn't worry about getting on a team too quickly. The LAST thing you want to do is join a team that's not a good fit for you. You want to make sure of is that you find a team who's playing style is in line with yours. The example I always bring up in this respect is my team, Dagger Unit, and another team, Immortal Casualties. We're both decent teams, and we're all pretty good friends, but our styles of play are totally different. IC specializes in more of a direct, fast paced, in-your-face kind of play, and the team is made up of a bunch of gun techs that are obsessed with building guns that fire 50+ rounds a second, whereas DU focuses a lot more on maneuvering and stealth, so our pace is naturally a little slower. One style isn't necessarily better than the other, but the main idea is that you want to find a team that suits your style of play. You don't want to be someone who is sneakier than the invisible woman at a ninja convention and find yourself with a team lead who doesn't really focus on stealth as a means of beating an opponent. And the only way to make sure that a team is right for you is to play a lot and play with a couple different teams over a six-month period or so.
And like just some kid said, don't forget to consider team uniforms/loadouts when you join a team. On DU, there are a couple of guys who are complete gear whores who really want specific uniform and loadout requirements, but there are also a couple of guys that are content to wear a full loadout that costs less than $100, so that's one of the things to watch for.