I had originally posted this in the Skirmish section, and it was pointed out that the topic should be seen by the broader group.
The answer is (obviously) yes you should.
With the onset of regionals, I feel like I've see a few posts here and there about people wanting to get into the competitive scene, and all I can say is DO IT!!!!!
From personal experience, competitive gaming had a stigma of cutthroat gamers that broker no nonsense attitudes. Don't ask why I thought that, but that didn't sound fun. However, a buddy and I decided to play in a local store tourney and that has now flourished into a fantastic experience. Between my local area, extended area, and this forum, the community is generally great. I've played in several tourney's and a sizable regional last year, and have yet to play against an opponent that made the game un-fun.
In fact, if you don't have all the expansions, who cares. Put together a list, play it thoroughly so you know the nuances of it, and chances are you will be competitive in most of your games. I learned an exceptional amount about the game after getting worked over in my first tourney. Discovered that figures I wrote off as crap, actually were great.
At the end of the day, there is attendance swag, and now-a-days top 8 get a pretty sweet new set of die (impress all your friends).
All you need....List with figures and deployment cards, in game tokens (damage, focus, etc.) and tiles for building the tourney maps. Many players have the mats, but bring the tiles just in case.
Check out this thread:
Play on Vassal for practice (online skirmishes). Ultimately, just jump in like you said. I was very hesitant at first (I was worried it was going to be totally cut-throat), but couldn't be happier now that I did.
Lastly get all your friends to play!
Edited by wannabepudge