I don't have a huge heap of experience myself when it comes to touching naked men, however, I have enough to know that just about any way will do, as long as you don't grab and twist. But that should be bloody obvious. Naked men usually aren't in any position to be picky about such things, and would just like to be touched. Please?

Note to the male readers who will take righteous offence at this: this search was obviously being conducted by a teenage girl worrying about going that next step with her boyfriend. I think you'll agree that any teenage boy whose girlfriend is going that extra step is just happy to be being touched. Just thank your lucky stars that more teenage girls don't understand the huge power they hold over their male compatriots. Life would be very, very unpleasant if they did.