In your specific situation, i would recommend you watch the entire episode below, they will give you products and techniques that will help with your question specifically with regards to the neighbors.

I will warn you though, this is a holms on homes episode.. So, they pretty much tear everything up and make it arguably the best possible.


http://www.dailymotion.com/video/xd6yok_soundproofing-room-home-to-avoid-ne_people