I would really avoid talking about your ex until the comfort stages. During attraction you mainly want to talk about yourself, your mates and the surroundings you are in, and a little about her. The best way to travel through the attraction stages is to ask a broad question about her that will allow you to expand and have alot more statements available to say. Alot of broad questions are easy to come up with in the situation, it's just the opener. For instance if she is quite helpful, jokingly ask her if she is a hairdresser. If she's not, say she should be, but after a bit of training, because her taste is odd (little neg there, aim for odd or unusual, instead of saying she is downright bad)
It is important to allow her to believe that she is LEADING the conversation, but don't allow her to take control of it... if you get what I mean.
Besides that, you're french. Doesn't this come natural to you?

Oh, and if she isn't french, try a little bit of french on her, a bit after the initial attraction.
EDIT: I just got a good idea, if she isn't french, you could say a shitty opener IN french, and then go "oh, sorry I thought you were french, you look french" or something. But make it better than that, that's just an example.