Light bondage will probably suit you very well to start. Just get some nice, soft cotton rope from a hardware store. Maybe start with just tying his wrists together (wrap the rope many times around rather than just once; this will prevent it from digging or cutting off circulation). Or you can always tie one end to each wrist and the other to the bed frame (the metal bars under the bed that hold it off of the floor), again, wrap the rope many times around his wrist to prevent it from digging into him. Bondage can be very complicated or very simple, it's all up to you. Don't be upset if it doesn't work out how you planned right away, either. Just like anything else, it takes practice to get good at it, for both of you.

So long as you never ever leave him unattended while bound, it's pretty safe. Keep scissors handy just incase you can't get the knots out.

Did I mention don't leave him alone like that? Keep in mind he really will be helpless. If there is any kind of emergency, he will be dependent on you to set him free. And this fact will probably make you both very, very hot.

Good luck!