How would one go about soundproofing a room?

There is an episode of "How I Met Your Mother" where the architect character (who really needs the work) has a client that wants him to design a big house. Sounds good till the client describes the "laundry room" with soundproofing, a French drain and hanging chains!

Hi Ms. Whispers trust you are well, you have another great topic, I used alot of guitar center foam and cones, along with a thick and insulated boarding with double foam over the window in my house, works great and even went in front yard and played music real loud and heard nothing, its so cool to play and have music on too and be able to let loose, super sexy....My best to you and all the time and help you do here for all of us....