When teens feel secure in their own little private corner of the house, they are likely to feel more trusted and competent — getting a valuable foretaste of independence and, since they aren’t so inclined to fight for independence, they are more likely to share more of themselves with parents!
Also, respect your teen’s privacy regarding his body. Young teens are often quite self conscious about body changes. They can be devastated by teasing or critical comments. Don’t ask invasive questions about sexuality, like "How did you make out?" This reinforces peer pressure for your son to be sexually active before he’s emotionally ready.
Do let your teen know what your values are, and your availability to discuss any matter, or to answer any question.
Accept your teen’s separateness — allow areas of privacy in his life. This can help him to grow up to think for himself, and to take more responsibility for his own life.