Always give her an escape hatch if you are seriously approaching someone--it increases spontaneity as well as her sense of safety. As you drop your hints, watch and see if they are being returned...respond to her hints. You, of course respect her supreme right of rejection, since you must occasionally invoke the same. Rejection is, after all one of the great risks that makes the courtship stakes so exciting.
You know the joke. Question: What does a lesbian bring on the second date? Answer: A Uhaul. Not every flirtation needs to end up physically in sex or in long term partnersip...if you are flirting with anyone--as a friend or as a potential partner--you must have seen something in them that you liked...and their feelings, their person, deserve your respect and consideration. If you are leaving, make sure you take your baggage with you. Otherwise you may have to go back and get it someday.
What are the essential ingredients of a good flirt? Describe your favourite seduction of all time, in detail, in terms of what was said and how you felt.	What have you unexpectedly discovered about yourself when you were flirting/being flirted with? What have you learned about community from flirtation?	Why is it so important to talk about lesbians and flirtation? What would you like to find out from a project about lesbian flirtation?

I declined at first, and then, for no particular reason, I changed my mind.
Proust