I think the issue of what happens to the cum should be addressed.
If you are a squirter, then your cum probably ends up on the sheets, a towel, or on the floor. I consider this waisted opportunity. His face, hair, or mouth are all better locations. If on his face or hair, he should let it dry in place and wear it like that all day. If in his mouth, swallowing is great, and snowballing back with you is also hot. You can also soak up any extra juices with a pair of panties that he has to wear for the rest of the day.
With his cum there are many options. If he cums in your mouth I would certainly have some snowballing fun. If it is on your chest or belly, he should spread the cum all over your tits using only his face. You should grab his head and really rub his face in it to get good coverage. Allow him to lick your nipples clean. Again let it all dry in place and then both of you can wear the dried crispy jizz all day. If he comes in or on your pussy this is just a straight up cleaning project for his tongue.
Keep in mind that for most guys, their interest in eating or tasting their own cum drops immediately after they shoot their load. Knowing this you can play it one of two ways. You can force it on him immediately for a punishment effect. This will probably be accompanied by a feeling of disgust, and may make him dread cumming the next time. The alternative is to wait a little while, gently play with him and lead towards more arousal and another erection. Then, as his interest in sex grows again, make him do his cum chore as the next step in your session. I prefer this approach as it lets his natural interest in the issue grow again, and cultivates an eager and obedient man who sees eating his own cum as a half way point in the overall arc of the session. Letting the cum sit on your belly or pussy while you coax him back into action is easy. If it runs down you side or down your ass crack don't worry. He'll still find it all and do his job when the time comes. It may actually allow for a little more cream pie to ooze out of your pussy. The real trick will be if his load is all in your mouth. Pretend that you swallowed it with pleasure, but give him the "shhh no talking" sign and just rest in silence. A little stroking, moaning, and rubbing will do the trick to get his mind revving up again. Once you know he is on board with more fun, maneuver to be on top, straddling him. Sitting on his limp cock, sliding your clit along its length, place his hands on your tits. As the fever builds you can then lean forward, pin down his arms over his head, and go in for the kiss. Start out with lips only, and then invite in his tongue and open mouth. The surprise that you've been holding his load all along, saving it for him, will be impressive and humbling. Your physical dominance on top of him is great. But there is a mental component in that you have already endured with the cum load in your mouth for quite awhile, that now he must take it and swallow it. You have already out done him regarding this task. He is the lesser if you two. He has many loads of cum ahead of him, and may never reach the point of being your equal. You have taken all he could give, held it, and then given at all right back to him on your own terms. You win.
If he needs a command, keep your eyes intensely locked to his. Pull away from his mouth just enough to whisper "Now swallow." After he swallows follow with "Smile," and then finally "Good boy."