One thing I want to get across to all single guys out there is this little idea right here: women do not just aimlessly look around at guys in a situation that is strongly equated with sex.
So, if you are at a bar or club and a girl is giving you repeated eye contact, it's a signal. Pure and simple.
How can you tell? How can I know for sure it's not something I'm mistranslating?
Because women will not risk having some random weirdo get the wrong idea. Ever. If a woman has any doubts about your flirt-worthiness, she isn't going to chance giving you the wrong idea. So, if you see her at the end of the bar or across the dance floor or three tables over, and she's making eye contact (or pulling the patented look away when you look trick), then you're in. Go for it. All the lights on the board are green.
In a setting where the sexual tone is clear, women don't chances on sending false signals. It's just that damned simple.