The above posts are all right. You should get some more training and experience under your belt. Train until your reach your natural maximum genetic potential. Then start some light AAS to break that barrier. After a few years cycling AAS from light to hard cycles, you should give GH a try. I have never tried GH so I don't know the potential it would yield. But you are young bro, if you need a little boost at 20, do some light cycles here and there. Then, when you get serous and want to make BB a major part of your life, seriously look into all factors involved (food, sleep,training,etc...) and try some heavier cycles and see how your body reacts. You may blow up, you may not. Either way bro, you need some more time under your belt. Go to school and get an education (you can train after your classes) so you can afford the GH! Good luck bro, I hope you reach your goals.
Arias