Sociologists have carefully studied this ancient mating process where eyes are used to get a mate.
They discovered these two parts of the process: The first step is to make eye contact to show specific interest.
Here are some of what is going on that makes most guy's knees weak when approaching a woman to say his opening line: If you make his approach look acceptable to all the others there, he will be especially grateful and immediately like you!
Looking down is an ancient mating signal indicating it is OK for him to approach you now.
In a few moments, you can casually look up to see if he is approaching or is still there watching you.
Often this is done by offering you something like a drink, food, or cigarette so that you will reach out and accept it.
That is a symbolic gesture indicating that you accepted him.