Warming up before a benching session I might suggest the much overlooked push-up. Prefered between a push-up stand, blocks, chairs, etc. Or light DB presses with a full stretch. Pullovers help the muscle and joint areas. Best to warm-up with the same, or near the same, motion of the exercise your going heavy with. Benches=push-ups, squats=bwt squats...sissy for a complet quad stretch...Hindu squats for a total lower body warm-up.