Since men are aroused by visual stimulation anything you do that he sees is going to get him hornier than touch. That's why men don't close their eyes during sex. They need the continual stimulation of seeing you. He is excited that you are touching his penis but he also needs to SEE you touch his penis for him to get super excited.
So anything you can think up that is sexual that he can see you do is going to do the trick. Like someone else said, something as simple as a striptease might be what you are looking for.
Is he a masochist? Have you though to ask? Bite him a bit, be rough, grind up against him. He will f***ing love that. Wear a skirt and grind your pelvis into his body. Suck on his ears. All of these are great techniques.
A lot of guys like boobs so you can wear something very cut like a loose open front top where he can so a major portion of your boobs. You could always spread your legs and let him see you're not wearing any panties. Be creative about showing off parts of your body or just start walking around naked when you're alone with him.