Bleh, why join clans? Do the same like me;
Be independent! You don't need to hear shit about clan when you joined, or get flamed/trolled/whatever by other players when online. Only good thing in clans that they keep Trem scene active. That's my (only) positive thing about clans. Oh, and they provide excellent discipline in teamwork.... Well... maybe not all.
Oh, And I've never been in any clans, not even in other games (ET, Quake 3), but seen enough. Too much.

And maybe I said this too fast, but my opinion is still to stay independent.