To enable maximum tension on the targeted muscle, you need to make sure that your pecs are doing the majority of work during every single rep. Dumbbells have the ability to place slightly more tension on the chest muscles than a barbell and they also keep the muscles under tension for longer because of the greater range of motion, so consider
incorporating dumbbell presses to your chest routine to reap this benefit and exhaust your pecs more thoroughly.
Of course you will also want to
incorporate exercises like barbell and
dumbbell rows, pull ups, chin ups, leg
presses, shoulder
presses and a few other compound exercises to get that «bodybuilder» look and give the muscles a different kind of stimulus.