It’s all about the setup! with the two different positions, bodybuilder or powerlifter. In my personal opinion, I think that you should learn and train with both. What is the point of having a strong chest and it looking like crap? Utilize both and learn from your body and what it gives you.
-Lie flat on your back and grab ahold of the bar with an underhand grip
-Pull yourself underneath the bar so that it is over the upper two abs
-Contract the lats nice and tight
-Make sure that your hips are still in contact with the bench
-Keeping the back nice and arched making sure that you have your traps slammed into the bench bracing for the weight to come
-Feet can either be right out in front of you or tucked underneath the hips.
-Lie back and drive those traps into the bench without having a major arch in the lower back
-Have good stability and good range of motion for maximum tension
-With your feet firmly planted in the ground you can now use a little leg drive
-Now it’s all about the timing
-Keep a little tension in the legs as you lower the bar
-As the bar touches the chest drive the legs and explode the bar off your chest
If you want to really feel your bench press then you will watch your bar path both in the eccentric phase and the concentric phase. You want to make sure that the bar touches right below your nipples. From there you will feel the effort from your leg drive.
-Make sure your elbows stay tucked on the negative and on the concentric until you reach the top of the movement then you want to drive the elbows.
-Make sure that you do not let your wrists go limp!!!!!! If you do, there is a good chance you will break your arm!
*Personally I have found that to make sure your elbows and bar follow the right path, find your grip! As far as grip I mean width of your hands and the placement of your thumbs. When you first start out you will want your width to start with spreading your fingers wide. Place your thumb right on the edge of the rough part of the bar, that is your width. Now you need to decide whether you want a closed grip, false grip, or my personal favorite sticking the thumb straight out along the bar.
*Remember, listen to your body! If you have a problem locking out at the top of the movement then there is a weakness in the triceps. If you have a problem just getting it off your chest then your body is telling you that your chest is weak along with your lats.
Only other option is you are trying to hard and have way too much weight on the bar!!! Leave the ego at the door and it will work out better for you in the long run. Be able to fill your t-shirt for many summers to come!!!
16 Week Progression for Building a Bigger Bench read more here.