The following are my recommendations on how to set up to maximize your raw bench.
Arch on the bench as high as possible while keeping your butt in contact with the bench. You can achieve this arch two ways. You can set your feet first and then lift your head up to the bar and forcing your head towards your feet. You can also set your shoulders first and walk your feet back to your shoulders. Arching will reduce the range of motion that you have to push the bar which will reduce the stress on your shoulders and allow you to move the most weight possible. It's not bad for you; it's not going to place unnecessary stress on your back.
At Orlando Barbell many of us place a foam roller under our backs on our warm up sets to help loosen our erectors and to force us to arch higher than we could on our own. Once we get into our heavier sets we remove the foam roller but try to maintain the arch as much as possible.
Force your shoulder blades together. This will help to elevate your chest reducing the motion while once again reducing the stress on your shoulder joint.
Get your feet as far underneath the bench as you can with your legs squeezed into the side. This will help to maintain your arch while helping to force your butt into the bench rather than up.
Grab the bar as wide as you can while still being able to keep your elbows directly beneath your wrists throughout the motion. If you grab too wide or too narrow you'll lose leverage. The best analogy of this is to position yourself with the same width as you would for a push up. This would be your strongest natural position.
Once you're in the right position your eyes should be directly underneath the bar. Take a big breath and fill your chest with air before lifting the weight out.
Force your shoulder blades together again once the weight is unracked and settled. Sometimes having weight on the bar allows for you to force them together to a greater degree.
Take another big breath before lowering the bar. Then take the bar to the highest point vertically on your chest or upper abdominal area. In this position your elbows should still be directly underneath your wrists. If you touch too high or too low then you'll lose leverage. You will most likely want to take a breath each rep although you may be able to complete 2 or 3 before taking another one. Do whatever works best for you while being able to maintain your position throughout.
Keep your elbows at about a 45 degree angle to your body. If you tuck your elbows too much you'll lose leverage, if you flare your elbows out too much you'll place too much excessive stress on your pecs and rotator cuffs.
Don't bounce the bar or excessively pause. Just touch the weight with control and press back up.
When benching onto boards touch the weight with control (don’t sink it in and use momentum) the same as you would off your chest.
Press at an angle towards your head. If you press straight up or too far back you will once again lose leverage. You should angle your elbows out at the top to lock the weight out over your line of vision where it started.
Thanks for reading, and never give up!