The thing is I know they want me to go talk to them but I have no idea what to say to a random girl.
Most Helpful Girl
Walk up to them and say "Hey, how's it going?" or start the conversation off by giving them a compliment. "Your hair looks very nice." or you can even say "You look so familiar." (even though that may not be true, it will grab their attention. "You know what...you look just like this girl I used to work with a while back, very attractive like yourself." <will get them smiling.