Sorry, I may have been a little too harsh in my criticism. I just designed a website for a detergent company using environmentally friendly products - guess what?
The site (light-blue fade to white - with reflections) looks like your poster.
I think in targeting any segment of a community, you have to research what makes them look up and listen.
Teens seems too big an objective to target effectively. Try narrowing it down. Maybe you need a series of posters for different sub-groups.
It may be best to ask yourself: "Where will this poster be hung?"
Hmm.. I like the idea of narrowing a set of posters down to where theyll be hung. The thing is though, what differences would be needed between ones for say, a library, a youth club or a leaisure centre. I cant think of differences that would be needed.
As for what do teens look up to, that is a very hard question to answer. Everyone is different in what they look up to. I guess good choice of colours would attract almost any teenager and also something modern looking too.