Something that's kind of awesome to do in a place that might have blacklights is this: take a yellow highlighter and draw designs all up and down your arms. You probably can't see it in the regular light but it'll glow in a badass manner ^_^
The only rave I ever went to was in London, and all the girls had weird themed outfits. Like skanky cavegirl, but in a cool homemade way, not a lame halloween costume way. A bunch of dudes only had white undershirt tshirts, or wifebeater shirts and cargo pants.