Always wet, at home I use Curel Ultra Healing lotion, it's slick and one application lasts for the whole session. On the road I'll use whatever lotion is in the hotel room.
Most of my masturbating sessions are done dry but when I do feel the urge to "go wet" I always use a little margarine to glide things along. I find that margarine keeps lovely and slippery for ages and it also makes a great "squelchy" sound as I masturbate. If anyone wants to try this you must remember to give your cock a thorough washing afterwards to get rid of any greasy deposit which remains
Always wet. Astroglide is my favorite. As far as cleaning up, I will wipe off the excess,but leave a film of lube on my cock and balls.It feels good ,and reminds me of the orgasm I had.