My info:
Almost 25 yo
137 lbs
5' 7"
Recently out of the military, two full years of my five year enlistment were dedicated 100% to lifting. I have researched how the body works, exercises, nutrition, supplements, etc and dedicated a lot of time to lifting but I have never seen good gains. I have a very high metabolism and it's always very hard for me to gain weight. I have tried MANY supplements of different kinds which all seemed to do very little. I'm tired of minimal gains and am looking at stepping up to the plate.

1. What should I be reading?
2. What is recommended out of all my options/what to take?
3. And any other information I need to hopefully make this happen safely.

Thanks a lot