Well, in terms of mutual msturbation, me and my boyfriend would slowly take it up in notches, as in what positions we would take, passive masturbation (with a counterforce, like a pillow or a stool), how many orgasms we would achieve and in turn how long we could hold off our orgasms. Since our sessions became longer and longer, my boyfriend delayed his cum until the end of the session, so usually I did the same and delayed, taking as much stimulation as I could before cumming became like an instinct. Sometimes, I would cum about 3 or 4 times because I could, but men can usually only cum once in full orgasm and then with a secondary cum that isn't as strong. Then it stops...apparently.
So, I was being polite in delaying my cum, which, quite frankly, was much more arousing and very satisfying as we concluded our sometimes 2 and 3 hour sessions.
However, it depends on how passionate you are about helping one another masturbate. Me and my boyfriends were terrible at the start, and learned through experimenting and just having fun, really.