Well, it's a bit tough for someone outside that context to come up with a surefire method, but here are some tips that might work for you:
Spend a bit more time learning about the ups and downs of life over there.They make good topics for discussion.
People in this age group tend to open up to teachers and tell them things they would never share with parents. Pin them down and exploit them.
If you can afford the risk, wind them up a bit. Never agree with them.The secret is you must be ready to think ,on the spot,of a counterargument for any argument they give .
Learn a bit of Spanish or whatever language they speak over there.
Sometime, ask the students to suggest a topic. They'll love it.