Teenage stress is quite a mixed bag.
One one hand, teenagers are still children, used to be taken care of and protected, living at the mercy of their social environment. On the other hand, they are growing up physically and mental and emotional growth is expected from them as well (at least proper mimicking of it).
Being torn between the the need for power and responsibility, social acceptance and the innocent attitude of a child towards life, teenagers generally go through a crisis of identity, and even after an identity is formed, it can take a long while to gain confidence in that identity.
Unlike childhood stress which can be relieved by crying, and adult stress which can be prevented by conscious decision-making, teenage stress can be overcome only by creating the person who you want to be.
It is unfortunate that modern society is geared towards prolonging this transitional period, and it is even more unfortunate that some people never mature, only grow old with rigid masks on.
The main points of overcoming teenage stress in the earlier stages are clarity and confidence, and in the later stages responsibility and love.