I often pick up girls on the subway, and here is how I do it, with an example. The principles outlined here apply to almost any interaction you know is going to be short-term, such as in a line at a grocery store, or in an elevator, where there is a likely hard stop.

There are a few reasons why it's often easier to pick up a girl in a subway than on a street or a club. First, time constraint. Any time constraint makes a girl more open because she knows she's not going to be stuck with you.

Second, display of confidence. It takes some balls to open a girl on a subway. That already shows you have high value.

Third, standing out. Most girls have been approached in clubs. Almost no girl has been approached on a subway. As soon as you open, they're going to be curious.

So here is the FR:

I was on a train platform, dressed in black jeans and Columbia jacket. (The first rule is that you have to be dressed neatly and ideally, professionally. If you're in tattered jeans you might do OK with another hippie chick but not a normal chick. You have to look nonthreatening.)

I see a girl, HB7ish, thick, on her iphone tapping away like mad. I open her "you're going to break that phone tapping away so hard at it. Who are you mad at?" She smiles, and tells me she's on work email. I banter back and forth about how they had better be paying her well, but she keeps going back to her phone, all the while smiling. I normally would persist, but it looks like she's stressed out about her work and my train arrives so I bail. (However, now I'm warmed up)

As I'm getting on, a girl flashes by me, and while she's short, maybe 5'2", she looks good and has a hot body. She sits down and I sit on the seat ahead of her and I turn around. (I would have normally sat down next to her but the train was mostly empty) I put my arm on the back of the chair and open her immediately, "hey, you look Venezuelan, are you from there?" (In the subway you have to open immediately. There is no time, and you look like a creep if you don't open immediately). She smiles. with a bit of shock, I realize she's actually an HB9. She looks like an exotic version of Monica from Friends. Perfect bone structure. Probably one of the 3 best looking girls I've seen in the last few months.

She replies, "no, but close." I stare for few seconds and say, "half Asian." She nods, "half Japanese, quarter Mexican, quarter white."

I frown and laugh. "That wasn't close at all!" (I break rapport by disagreeing) "Were you sleeping during geography class?" She laughs and says, "well, Mexico is in S America too." We banter back and forth. She tells me where she goes to school. (I am trying to establish where she will get off the train, you need to get her contact info before then). She's throwing me IOIs, staring at me. I'm teasing her, asking her if she's vegan (she's save-the-world girl).

Then disaster. The train stops, and she gets up, "well this is my stop, good meeting you." I reflexively say, "nice meeting you too." I was taken by surprise, because I figured she would be getting off near the school, and didn't get her contact info. Bad technical error.

Compounding it, I said goodbye to her instead of "I'm getting off here too." Girls get very creeped out if you are following them off public transportation. What I should have done is get off at the same stop, and then suggested coffee or tea. That way, I turn following into leading. At the least, I would have number closed.

As an addendum, though, I think in this case I should have followed her out even after the error because she was throwing off a lot of IOIs and as the train pulled out, I saw her looking wistfully at me. She was probably hoping I had gotten off. I think I could have possibly F closed her in retrospect.

So the key to subway pickup is to open immediately, establish how long she's going to be on the train, get the contact info as soon as possible, and then ideally try to pull her just as you're getting off so you're not following her but leading her.