Most men have pickup lines, whether that be just a hello and introduce yourself (one of the best I feel) or whether it is some witty one-liner you spent 6 months in your bedroom coming up with but only you laugh at… Women expect a pickup line to come, and if you do that then they have a million anti-pickup lines which they can use to get rid of you. Instead just be honest and polite, tell them you think they are looking really nice tonight and that you just thought you’d come over and introduce yourself while you had a chance, and she will be so surprised at your casual approach and lack of smug cheesiness she is far more likely to talk to you as she doesn’t feel pressured.