Alternately, just let him cum on his own belly. No muss, no fuss, no aftertaste. If you must spit, try your best not to look despondent or green about the gills. Just grab a Kleenex or take a quick trot to the loo, spit, rinse if you like, and get your hiney back in bed for more fun. Swallowing should be pretty self-explanatory.
Sharing can be a lot of fun, too.
As if it weren't already immediately apparent, when it comes to oral sex, I'm what you might call a fan. I like going down on my lovers. I find penises attractive. I like the way they feel in my mouth and on my tongue. I'm also an inordinate fan of the power and control that comes along with giving a partner really good head.