I've been put in a group with a very cute lass and today despite having an ear infection and feeling like shit I managed to get her laughing and I think it's fair to say she seems a bit intrigued by me by the look in her eye.

I'm not going to try to escalate too hard too early (I say that as though I know what the fuck I'm doing lol) because it's a project after which we hopefully get offered work from one of several companies, so I don't want to jeopardize that if my attempts backfire and lead to dissolution within the group.

How can I keep things flirty whilst maybe escalating really slowly? If we still seem to get on ok by the end of the project I'll ask her out for a drink I guess

Basically how do you escalate more subtly with someone you see regularly?