I never use my hands unless the cock is uncut and then I only use my hand to pull back the skin a little and then I like to peel it back with my tongue and lips.
Ages ago when I was young (19 or so) and dumb and full of fear, I went to the adult book store where this guy who turned out to be our town's married high school sports director took me into a booth, got on his knees and gave me a blow job so intense that I fell forward and couldn't carry my weight on my legs. He actually held me up while I shot stream after stream of sperm down his throat. My cock was so sensitive that I tried to get him to stop but he didn't and I actually shouted.
After that huge ball drainer I thanked him and asked him where he learned that. He just smiled smugly. Since then, however, I've mimicked his technique and I've yet to have a guy not come unless he's pulling out to come. I take great pride in my ability to give a good blow job.