IT definitely wont hurt to warm up the groin, I always had the impression that whole area needed the heat because that’s where the ligaments are.
For me, Jelqing grip depends on erection level, Go as light or as hard as you need to go while increasing the amount of blood inside the penis, but not increasing the hardness if that makes any sense, ill try again.
I think the goal is to stay at the same erection level while getting more blood inside. Erection level being how hard it actually becomes, not truly corresponding to the size or relative size of the penis.
If your doing the newbie routine, are you at the same level of intensity as when you started? What worked for me was increasing the intensity by small amounts after every second off day. I would increase jelqs by 25, or I added some Ulis and memento mod on the Sadsak head girth exercise instead a couple times.
I am by no means an authority at this point so if someone comes in and says “clemski is a fucking moron don’t listen to that dumb ass”, they could be right. This being said, I have read a lot of stuff, and I have seen some good gains.
Hope any of that helps Good luck!