I actually only learned what the western flirting culture is this year. Post this to warn girls to avoid any possibility to cause confusions? I think the most effective ways to tell a girl's attraction from friendliness are: 1) constant pitch of voice 2)touching 3)long eye contact. Personally I think eye contact is the most surprisingly intimate action. That's precisely the reason why I don't like video calls. It's truely too intimate. But when a girl like someone, she'll probably subconciously look at his eyes. Just personal view.
I wouldn't say that eye contact could indicate whether a person is flirting or not. I maintain 100% eye contact when I am listening to a person speaking to me; to do otherwise would make me look disinterested.
However, in general I think they're good pointers. I do agree that it is intimate, that's why a lot of people are uncomfortable doing it.
