If you approach a two-set flirt with the less-attractive first, as this will naturally cause the better looking one to feel jealous and try to grab your attention. Also, this helps avoid the less-attractive one from turning into a ****-block as she is undoubtedly used to being overlooked when out with her hot friend.
My advice is to avoid the bars and clubs and instead hit the shopping malls, promenades, cafes etc... as her defenses will be down and she will be more inclined to be affable, enabling you more time and opportunity to engage her.
If she is shopping, ask her for advice on clothes for some special occasion...
Make her laugh as quickly as possible; once she laughs, she will be comfortable with questions.
