I've never approached anyone as either a Dom or a sub and really tried to start something that way. Maybe I'm odd but I actually, you know, talk to people first. Get to know them. Then if we like each other we can just go with the flow from there. I've had a couple of PMs from admirerers, I guess you could call them. Plus of course ones among friends.
Then again I never was one for bars or nightclubs either so I guess I'm just staying consistant.