I have always had poor (weak) shoulders & triceps. I was never able to do the chin-ups and even push ups were like hell for me. But since i started working my shoulders and triceps (lat pulldowns, MP, Close BP and pulleypushdowns) i thought they grew stronger. Now i can do 20 pushups without any trouble but the thing is i still cant do chin-ups. This sucks, it kills me and frustrates me like hell. If there is anything i would like to improve is to be able to do 15 chin-ups without help and properly (looks like a dream). Any help??? Also can somebody please provide me links or pictures of excercises like Barbell rows and skull crushers, cos i want to include them in my workout too for better shoulders n tries.