Sounds simplistic and self evident, but the more aroused I am the more pleasurable an orgasm's impact has on my body and spirit.
I occasionally masturbate with a young male friend, maybe once a month or so. Recently we talked about how witnessing each other's arousal heightened our own. To add to the arousal created by watching, I put a large mirror, one of those cheap wardrobe mirrors that attaches to the back of a closet door, and put it at the foot of the bed where we were propped, side by side, playing with our hard cocks.
Watching ourselves and each other in the mirrored image was incredible. Sometimes we reached over and helped each other stroke, or I'd caress his balls when he was getting close to his orgasm. He watched me and himself in the mirror, bringing himself to a wild, long orgasm.
My own climax followed shortly thereafter.
Seeing our mirrored image at the foot of the bed was like having four men lying there, playing with their cocks.