Be optimistic and keep a lighter always

If you see a girl or a group of girls smoking cigarette at smoking zone, act like you are there for smoking, do not stare or look at her for a long time but stand on a place where she can notice or see you and your activities:

Steps:

1) Check your pockets for cigarette, Specially on Jackets all the pockets...

2) Check your pockets of the trousers and take the lighter out,

3) Say "Oh Shit!" (a bit Louder so she can hear...)

4) Go close to her and tell, I think I forgot to carry my cigarettes with me, Do you mind if I would like to ask with you for it?

if you are non smoker, do it just to start the conversation, You can always say that you quit smoking when you meet her next time, that can be even more impressive...