Harm Reduction Emergency!

[drugbeat]

Ok, here is the jist of my problem. I know this girl who is still in high school. She lives in another city and wants to start experimenting. She is my girlfriends cousin and by proxy, I am the most knoledgable person in drugs that she knows. The thing is that she is going to start doing things soon and does not care about the effects or consequences. Every time I try and tell her the cons of something she goes on the deffensive and tells me to stop being like her parrents. This brings me to my questions.

1) How can I tell her about the pros and cons with out her seeing it as an attack.
2) Is this just the normal teenager acting out phase?

I know that when I was her age I researched everthing I took. I wanted to know the pros, the cons, the effects, the dangers. I just dont want her to put herself in a situation where she gets hurt or worse. Please people. you are the harm reduction sepcialists. How do I do this with out seeming like an over bearing authority figure?