Have a date tonite (surprise) but this one's different. This girl has a bf, I see her every workday (she works in the cafe at my work, I see her every day and say hi sometimes). She's got a bf, he knows we're going to just hang out but I want to make it more than that. She flirts a bit with me and we text/joke but that's about as far as it's gone, we've been talking on and off for 6-8 months now, first time hanging out (said she had stuff goin on before, who knows).
Maybe she sees me as more than just a friend after tonite? Or as a fb? who knows.
In the end I just want us to have fun and show her I'm better than her bf

Maybe we kiss, maybe we just talk. My question is, how do I do so? Do I do light kino, be a bit sexual, flirt and have fun? Or be casual about it, lay off the kino and keep labeling her as friend to her (but opting for more down the road)?