I haven't read most of the other responses, but (as another brand new team) my advice would be to do both. Visit local competitions, talk to the friendlier teams, see how it works and get a feel for the operation. (Also, watch the first season of the TLC show
..) Then practice, practice, practice. And towards the end of the season just jump in, find a small local competition and hit it. You might be surprised.
That is pretty much what we did last year, although our "small local competition" ended up being almost 50% heavy hitters. O_O We learned a LOT that we weren't going to get from practice, or from classes. (Things like "put your temperatures on a board where the whole team can see them so that tired people don't turn your pits up overnight"..)
This year we are much better prepared, solely because we hit that competition. (And we didn't come in anywhere near DAL! Somewhat a miracle given the number of mistakes we made..) its like driving - you can spend months in class, but until you actually sit behind the wheel you don't know what its really like..
PS: Visiting competitions will show you everything from huge trailer pits to 2-3 18" WSMs. At least the comps we've hit so far, the majority of the teams cook on weber backyard gear. (We take an 18" WSM, a home-built UDS and a 21" weber performer which - as Stoke&Smoke said - mostly handles lunch..) Talking to teams about their gear will also help you get an idea what you need.