So you want a big chest right? Who doesn't! Did you know when you're training your chest muscles it's also a good idea to hit a few sets of back too. Working your chest and back together can give you better results because it'll generate a greater force and contraction when lifting through the chest. If you just work the chest muscles on their own without any back work, the tension around the muscles is weaker which will then result in less force being generated. When you work two muscles like this you're focusing on your agonist and antagonist muscles which is a bit like a 'tug of war' contest. When the rope is slack, the force is weak however when it's taught it is strong and stable.
Give this a try when you next hit chest, perform some bent over rows in your warm up and you should feel a difference :)