A technique I've found useful in benching if you can't move up a weight is to have a spotter aid you in a weight which is a lot higher than what you can lift. The spotter holds the bar with weight up, and you slowly bring the bar down straining your muscles to the max. The spotter guards you from injuring yourself, and when you reach your chest, the spotter lifts up the bar with two arms placed in an equilibrium up to the starting point. I usually do this three times before my muscles are in fatigue.