Home Recording Studio: Build it Like the Pros by Rod Gervais
It's long, lots of technical jargon, and some of it will go over your head, but it's full of good info.
and KEEP THE PEACE! THE MUSICIAN'S GUIDE TO SOUNDPROOFING by Mark Parsons, which is more straightforward, and also written geared to drummers.
Some of the info in the two books contradicts each other, and neither book accommodates every circumstance you might encounter, but none the less, I read both books several times over when building my studio.
The wall you see in my studio are 1-3/8" special "dry wall" that is composed of 11 layers of materials. The floors and ceilings are the 5/8" version.
Every electrical outlet was covered with quiet putty, and every pipe in the bathroom was coated with QuietCoat prior to the drywall being hung.
It's not 100% sound proof, but I can pump my PA up to ear shattering volume inside the room, and walk outside, and barely hear anything.
In my prior studio I made numerous mistakes in attempt to cut corners.
I didn't take into account the outter wall of the detached garage was just stucco with no wood backing, which meant the outter wall was really thin.
I insulated, and then put up one layer of fiber sound board, and a layer of drywall. Which was simply not enough mass to be the least bit sound proof.
For the inside, I found a "cheap" acoustic foam from a place in NY. And I covered every single inch of wall with it, but sound still bounced around inside as if there was no foam.
My current room has far less foam, but I paid for the good Auralex stuff, and it controls the sound 100x better, despite having less of it.