The biggest guy in the gym doesn't always bench the most weight. It's the guy who knows how to bench. Great technique allows you to press more poundage without injuring your shoulders. Take these tips with you every time you get beneath that bar.
Take a deep breath before you lower the bar to begin each rep. Let the air fill up in your belly and hold it. This increases intra-abdominal pressure, stabilizing the spine and creating a tight feeling throughout the body that will make you instantly stronger. You'll get a springlike effect when the bar reaches your chest. Attempting to take the breath while lowering the bar(as most of us do) will cause you to lose some tightness. Note, however, that you may want to hold the breath if you have high blood pressure.
Don't let gravity lower the bar for you. Pull it downward by engaging your lats. Think about leading with your elbows and keep them tucked close to your sides. Your upper arms should form a 45-degree angle to your torso when the bar is at your lower chest (don't bring it down to your mid pecs, but to the sternum).
Lift in an arching motion. As you press the bar up, think about pushing it from your sternum toward your face. This brings the triceps more into play. You'll need to find your body's own "groove" so that, at the top of the movement, the bar is in a direct line above your shoulders, where it should feel almost weightless.(by Matt McGorry, C.F.T/mensfitness)