Privacy for Preteens and Teenagers

This is a tricky one.  You want to give your daughter privacy.  As she matures, she needs to become more independent, and having privacy is part of independence.  However, she is not yet an adult, and she needs your wisdom, guidance, and protection.  

My recommendation is to be very transparent with her regarding the situation.  Explain that you want her to become more independent and have some privacy, but your job as her mother is to guide and protect her.  She does not get to demand privacy.  If you find that she is abusing the privacy that you give her (read: she is hiding inappropriate behavior), there needs to be a consequence.  Conversely, if she feels like you are being nosy and not giving age-appropriate privacy, you should try to listen to her concern and possibly give her more space.