See if there is something about the person to see if there is a nongeneric opening. If she is holding a book, ask about the book. If it's a romance novel, talk about the difference between girl books and guy books. If she is carrying a newspaper of magazine ask whats interesting today.

If these are a little difficult practice on people who dont count. By that I mean people who you dont care if you never see again. The elderly are often a bit lonely and love to chat. Or a girl you would never ask out. (You could be wrong about that.)