My chest is a weak part as well, but came up a bit (naturally) doing a powerlifting program hitting it 3x a week with massive volume (Sheiko)
Training shit once a week as a natural got me no where. 2-3x a week was best. I guess because of that whole '48 hour anabolic response' thing versus a guy on slin/gh etc that stays anabolic for far longer. I also agree with deceiver on mainly just hitting compounds.
I also notice the body parts that grow best for me are usually body parts I can train with exercises where I feel a deep stretch at some point during the movement...for example it feels like my lats are going to tear off my back during pullups, but I can't feel a stretch in my chest on anything but a specific hammer strength machine when doing presses..my shoulders always take the stress. Hell, I even feel a better stretch in my shoulders doing lateral raises than I do dumbbell presses for chest. Sure enough my lats and shoulders are far better than my chest.
Genetics and structure rule at the end of the day