Interesting tip I got from Jesse Burdick in one of his videos that the above picture made me think of is that you should do your best to keep your elbows above the level of the bench. The higher your elbows when the bar is on the chest, the stronger you will be off the chest. You will notice he is not arched in that picture. If he arches his spine, the bar would be higher when on his chest, elbows would be higher and he would press more. Not saying he doesn't do this when he presses properly (I'm pretty sure he has close gripped 230+kgs
) just something that picture made me think of.