Work harder than anyone you know, and be lucky enough to be blessed with the genetics it takes.
To make a muscle grow, you must force it to go beyond its capabilities. The most potent way to apply that force is to train to failure. Training to failure means...the muscles are forced to grow stronger and bigger
Professional bodybuilding is a sport of total dedication. You must dedicate every aspect of every day to the attainment of your goals if you want to succeed. It is not enough to merely go to the gym to "work out." You must put all of your concentration and focus on each rep, on each set, on each exercise to have a successful workout.
I don't have a favorite body part nor do I have a favorite exercise. Everyone who is honest prefers machines over free-weights, because machines are more convenient and cause less muscle pain and require less concentration and are generally less dangerous. BUT, if you like to have real gains you have to train hard and heavy, and you have to chose always the LEAST favorite exercises which actually give you the best possible results. So go for the least favorite exercises, the free weights... and go for the muscle pain!
Plain free-weight squats work better for me than anything.
