First, Welcome to the Cafe!
Lots of good input already. I agree with all of it. In moderation, it makes football even more enjoyable. In overkill, it takes away from the game, for me at least.
As far as your favorite team, it's nice to go for the double whammy of having your favorite team's players on your team, so you're not just rooting for your team, you're rooting for your
team. As a Colts fan, that's been pretty easy for me
Start small and simple, if you find your interest and comfort level growing, expand. Join additional leagues, experiment with auction/keeper/dynasty leagues, etc.
Just remember, the whole point is to have fun. Unless it's a money league. Then the point is to win, and have fun in the process
I used to think FF was sports dungeons & dragons. Then a league of friends/coworkers started in 2001 and I joined it as my first league. Been doing it ever since. Expanded in to fantasy racing, fantasy hoops, auction leagues, fantasy playoff leagues... there's no end to what you can do, if you're willing to put the time in and it holds your interest. Just be wary of getting so involved that it starts to feel like work to keep track of all your players and adjust your rosters, etc. Fortunately, if you're in one league doing research, it applies to all your leagues, so it's not like two teams is necessarily twice the work of one team.
Have fune! You'll find loads of advice around here, and a plethora of fine people ready and willing to help with your questions. When you view the list of forums you'll find subforums that involve injury and player updates, sit and start questions for weekly matchups, and the Fantasy Football Cafe homepage has articles published regularly dealing with all things fantasy football.