Hi guys!
I got two questions for you:

- What's the best opener in order to know university girls in cafeteria?
I mean, what to say if:
1) She's alone
2) Group of girls
3) Group of girls and guys

- There is a facebook group for the summer session (july) of my university where many studying abroad students (americans) joined.
1) There are many girls in this group... what should I do? Should I text someone through facebook before they start the summer session or should I wait to meet them at the university (small university -summer session: 500 students-)?

Thank you very very much for helping! I appreciate your help every time.

You don't want to damage your chances before you even start so stick to small talk.

rumours can spread liek fire at uni. Pretend that she will share your message with all her girl buddies. If she doesn't like what she sees, she will let everyone know.

However you could send a message like

"Hi (insert name) you seem fun and adventurous, the kind of people want to see at (insert University name) which course are you studying?"

Thank you very much man! I will!