Say "Are you on the edge? Yes? Good."
"Do you want to cum? Yes? What will you do if I give you permission?
Get promises. Some can be chores or gifts, but remember to add some sexual stuff to keep it interesting for him.
What kind of sexual stuff? Have him promise to lick you to 2 orgasms before he can cum. Or, have him promise to lick his cum out of your pussy until you orgasm twice. (trust me, he will like it!) Or, if you don't want to be involved, have him promise to cum on his chest and suck it all off his fingers. (see how fun this can be?)