I’m cut, but I think the same technique could apply. I take my non dominate hand making a “V” or inverted piece sign and push on each side of the unit. This is for holding back the fat pad exposing as much of the base of the unit as possible. I then use olive oil as a lube on my unit. I create an “OK” grip where the pinkie is away from the body, getting the OK as close to the base of the unit and stroke outward stopping before the head. You can do this sitting down or standing up. I prefer to do it in the shower or bathtub so you have the unit heated up from the hot water. I start to get EQ after about 20 strokes, so I have to stop and wait a bit to subside and then continue. My bathtub has a seat and I like to drop into the hot water while waiting for the EQ to subside and heating up the unit again. I continue this until I’ve done 200-300 jelqs .
Since your uncut, I would probably just leave the skin over the head.
Hope this helps.