Chances are you'll be going up against people with no real skill either.
My only tip is to not underestimate small, fast hits. The damage racks up quickly enough and then it's easy to finish the person off. I see so many people constantly going for big hits and getting their ass handed to them because of it. If you can't predict peoples movements well enough to land a solid heavy hit, or know when to bail if it wont, don't bother.
Big characters are a lot harder to play well, and most competent people playing speedy characters will just murder you.
Not much else I can really suggest. I played Melee way more heavily than Brawl, so that's the best i've got.