I like rock/metal clubs - though just walking up to people and chatting about shit and dancing isn't default, partnering up while bouncing and/or headbanging to the band on stage, getting together and becoming a two-man mosh-pit, or just knocking beer bottles together is more common, in my experience.
(Related comic: http://questionablecontent.net/view.php?comic=366
)Definitely a different game.
In my experience, you kinda have to be on level, and a little further with those who you want to attract - It's harder to keep hardcore goth chicks interested if you are blonde and have no piercings and shit. Another problem that may arise is if you can't demonstrate some knowledge about the music and such, since you are likely to get asked what you listen to (common practice in such circles to find common ground early)
It's also harder to find single girls, and girl-only groups are really rare.
As for the outfit, I only dress metal if the place and the "target audience" fits. What I really like and want to get is stuff from Alchemy Gothic ( http://www.8ball.co.uk/alchemygothic.b.html ) and similiar brands. No-band, badass designs, kinda flashy without being gay with glitter and shit, like most peacock t-shirts I see (yuck).
\M/
) and I've been called a 'walking metal encyclopedia' by some of my friends, so no worries about not having stuff to talk about when it comes to metal music... 
hehe
). Like I said, one wasn't hot but the other was damn hot, would probs give her a 8/9.