I know some people may say do not flirt with a server or a flight crew. I understand this logic (the server has to interact with you). However I sometime feel there is a geunine interest. Here is a technique I have used with retail staff.

After a brief conversation, I will ask if she will date a guy who uses that product. Let her answer. Then extend my hand and ask for her name. And I do not take my hand back. At some point she does. But the way she takes her hand back tells me if she has interest.

However I can't figure out how to make this kino work with flight crew. I am writing this from a flight where one of the crew members is giving me a huge smile and I am at a loss. The best I can think of is -- exit the flight and wait for the crew to come out. When she is exiting, try and hold her eye contact. If she does makes eye contact and holds eye contact for more than normal then I can approach her.

As I am writing this, I am thinking I can ask the server if the restaurant is busy all the time? And does she like to work at busy times or when it is less busy. Perhaps go there again once or twice. Talk about what I tried last times. And if she continues to banter say I want to take her to place ABCD which has the best DRINKS.