"How do you dress for kink/BDSM play? What significance does your attire have to you?"
Generally, the only thing I'm wearing for BDSM play are restrains and welts :)
If I'm feeling playful, I might wear one of my slinky pink nightgowns that drives Husband crazy, and a pair of snug black panties underneath.
If I'm feeling very daring, and it's daytime when Husband does not have time to "deal with" me, I might make sure he knows I'm wearing a garter belt and thigh-high hose, with a pair of translucent blue stretchy panties. This will drive him wild and keep him thinking about me the rest of the day (me, and my translucent blue panties). I'll pay for my daring later, of course...but that's part of the play, too.
But really, it doesn't matter what I'm wearing, the point is the way the clothes are taken off. Who removes them, in what way, how quickly...those are usually the things that help set up the scene.
We don't do cosplay or pony play, and the only thing leather he wears is his belt. We do dress up a bit when we go out to a club, but that's different: that's social, not BDSM play.
Maybe I should look into getting a harem girl costume....