I get opened a good bit, but usually don't realize until it's too late that I've been "opened" opened.
What causes girls to open guys is pretty simple: 1) she's attracted or at least interested, and 2) she's feeling randy enough to take a shot at you instead of choding about.
A girl can become attracted to you from afar if you're bringing the party, having a good time, congruent, etc. She'll spot you while she's value-scanning and might girl-open you, hoping that you'll think she's pretty and hit on her.
Girl-openers I've personally experienced:
Girl standing near me when there is no particular reason for her to be doing so. She usually won't even be looking at me (save a few glances), but she'll be standing where I can easily see her, and will usually be standing in such a way that shows off her face and neck and/or T&A.
One girl (either that I know or that I don't know) introduces me, out of the blue, to another girl. In my experience, Girl B (the one being introduced) has TOLD Girl A (the one doing the introducing) that she thinks I'm hot or whatever, and Girl A has taken proactive measures to hook her friend up. Girl B is being handed to you on a silver platter in this scenario; you've got attraction, you've got peer group approval, and it wouldn't be a stretch to say that you can then consistently close within thirty seconds if the energy is high enough. I've actually had Girl As (in some cases accompanied by Girls C, D, and E) physically PUSHING Girl Bs towards me to talk to me if Girl B thought I was hot but was really shy or whatever.
Girl will ask me a "functional" question ("what time is it?" "do you have a light?") and not immediately leave afterwards. The question is just her way of getting me to notice her, and she's hoping I'll move forward once I do.
Girl will go into the men's room to pee "because the women's room is full," walk out of the stall with no pants on, and start asking me rapport questions.
Girl will walk up and compliment you on something. I'm sure you all recognize this as an "AFC" opener. Well, girls use it too. And they expect it to work.
I've experienced this one only rarely, but my chick-friend Amazon has told me about it:
Amazon knows a lot of strippers. These strippers also happen to be raging nymphomaniacs, and also quite hot. They go out and try to pick up guys, actively approaching, showing interest, the whole nine yards. And they (the girls, I'm talking about here), REGULARLY strike out and don't manage to take a guy home. The reason for this is pretty simple, and Ozzie put it best: "There are no closers anymore. Everybody's chode."
According to Amazon, they go in full-on
Night at the Roxbury and/or "Two Wild and Crazy Guys" (old SNL skit) style, "hey baby, wanna dance," etc, and the guys will just chode the place up ninety percent of the time.
I am in no way suggesting that your game should revolve around value-scanning for girls opening you or trying to open you and then responding to it. But you should be ready for it when it happens, because it does. And if you're in state, you'll be ready to respond when you get opened.
Also, "Two Wild and Crazy Guys:"
[youtube]
http://www.youtube.com/watch?v=t9SaKYFR6ms[/youtube]
I hear ya on the eye contact thing. I've never been big on looking for that, but I guess I should start. The stuff I've listed is just the more "aggressive" girl-openers.