I suggest a kind of jelq that involves the lower part of the shaft, so that the glans (corpus spungiosum) gets inflated. At the end of each stroke, keep the glans inflated for 20 or so seconds.
At the end of each training session (non more than once a week) you could see striations on the glans. It's ok and they will subside soon.
For the uncut men as me, keep the glans always out. With the help of a glans ring if necessary. Some people like to wear glans rings. Not me: it's the sensation, though I like the idea of wearing it without showing, because the skin covers it.
A cockring - shaft only - I think is more effective for glans size and penis girth.