I did a great deal of weight training as a young fella, i did use amino acids as a supplement and it certainly helped me get stronger and also more body mass..
I always wondered if their was going to be any side effects later in life but researched that your body produces certain amino acids on its own, i just added more of the good stuff to boost my stregth and energy levels.
I was as strong as an ox to the point pound for pound with guys i trained with none ofthem came close to the strength i had to lift. I was strong before the amino acids supplements but once i took them i gained about another 15% - 20% on top of that.
The only other thing i could advise on training would be a really good diet and eat like a horse, stay of the grog and get enough sleep...