You'll probably get lots of variations on what I'm going to say here, but between us we'll probably cover everything so here's my 2p worth
First off, to help we're going to need more information from you...let me explain
When you say start, do you mean you want to start playing paintball, I'm assuming you've played before at rental days and you want to start more seriously but want to be sure
If you mean you want to start playing for the first time ever, well you don't need a team, a location would help people guide you to your nearest site and you can get in touch and hook up on a rental day.
If you've done this and want to move further, then there's a few more things that will help:
Do you have your own gear?
What are you interested in, walkon, magfed, tournament
See you don't really need to join a team to play if all you want to do is play...I've done it for years off and on, just rocking up at walkons and having fun with whomever was there. Joining a team does give you the advantage of likeminded people to play with but you'll need to join the right kind of team for what you want to do...and also for the amount of effort (and cash) you want to put into the hobby. The team I joined when I got back into the game plays mostly tournaments, some teams play mostly scenario games you'll need to get the right one for you
So, if you do need to join a team, to help us help you out:
Where about's are you based?
How far can you reasonably travel to play?
What sort of game do you want to play?
What kit do you have already?
What experience do you have?
think that's it, but like I say I'm sure others will chip up with anything I've missed.