This afternoon when I rode in the subway, a girl sat next to me, using her Iphone. She might read news or microblogs or some chat app. Her head was bent low. How can I open her?
Here is my answer if I meet the same situation next time:

Me:(Turn 45 degree towards her) (Situational opener)Hey, do you think smartphones make us closer or more distant with other people?
Her: Ermmm...
Me: oh, there is something on your hair(Negging her).
Her: (Touch her hair with her hand)
Me:(Transitional openers)Do you believe in telepathy? Think of a number between 1 to 4, the first number which is popped up in your head. Don’t say it. 3, Right?
Her:...

What do you think of my answer?

Sounds a bit gamey tbh.

"Whatcha reading?":
If you come with a strong male presence and she is into it, this is all you need for an 'opener'.
Then chit-chat about that for a bit.
Find out about her.
You tell her about yourself.
Take her #.