I oftentimes will see people bench press incorrectly. Many use too much weight, which will cause them to bounce the bar off their chest. This is dangerous. I also see people flare their elbows way to far, or they will lower the bar above the nipple line.
It is important to bench press correctly for a number of reasons. First, and probably most important, correct technique will decrease the chance of being injured. Second, if you use correct technique, you will likely see more gains (muscle size and strength). Finally, I have found that if you set up properly, and use correct technique, you can press more weight.
Here is how to bench press correctly:
1. Pinch your shoulder blades together and keep them tight. Keeping the shoulder blades tight will create a more stable surface from which to press. It also creates a shorter distance for the bar to travel.
2. Keep pressure on the traps and upper back. Do this by lying on the bench. Pull yourself up and towards the bar and then lowering your traps and upper back into the bench. Drive your legs into the ground. This should result in an arched back with pressure on the traps and upper back. Doing this will allow you to use the supporting muscles for the bench, your traps and upper back.
3. Squeeze the crap out of the bar while trying to pull it apart. By squeezing the bar hard and trying to pull it apart, your body will stay tight and your triceps will be activated.
1. Slowly lower the bar to right below your nipple line. Actually, concentrate on pulling the bar to your body. This will keep your body tight and muscles activiated.
2. When lowering the bar, tuck your elbows so that you can lower the bar in a straight line and so your lats will be activiated for the lift.
3. For max-effort lifts, make sure you fill your lungs and belly with air, and hold it for the entire repetition.
4. Make sure the bar travels in a straight line down and up.
5. Drive your feet into the ground, thus activating more muscles for the lift.
I just discovered the video below. It is from the Diesel Crew (http://www.dieselcrew.com/). It is an excellant video on bench pressing correctly.