Oh, just be yourself.
Actually, no: be yourself, but the yourself that can approach a stranger and start a conversation. try to talk about things that interest you, but might be broad enough that almost everyone would have an opinion on it. For instance, this weekend it occurred to me that I had no idea how far the moon was from the earth and knew that someone would eventually know. So the conversation goes "Wow, thanks for educating me on how far away the moon is. How the heck did you know that?" OR "Wow, isn't it kind of sad that two grown adults have no idea how far away the moon is? What are we, a couple of cavemen throwing rocks at it? ha..."
the thing was: I really, really wanted to know the answer. it made me look less like some creep who is just trying to scam on a babe, and more like some creep who is trying to scam on a babe AND enjoys trivia.
One thing I know for sure: do NOT be cryptic at all when talking to strangers. Having little in-jokes either with yourself or your friends can really alienate someone who doesn't know what the hell it is you are talking about. Case in point: last weekend this young lady came up to the bar and ordered 3 ice waters, but couldn't carry all 3 back to her friends. since she was a cutie, i was all like "oh, let me get that for you". when we reached her friends, I gave her the water, and she was like "Thank You". For some reason, I replied to this by saying "hey, no problem Sister Christian" and then left. About 10 minutes later she comes by and says "hey, you should really fucking watch what you say to people". For some reason she felt that I had insulted her, instead of just randomly referring to her by the title of a famous Night Ranger song. Lesson learned.
so take any of the above advice and do the exact opposite, and you should do fine.