My hands popped like crazy the first times I closed it as well, and still do when I don’t hit the #1 a bit.
First and foremost, forget you own straps(if you do). Next, heavy deads are a staple. I don’t think my job (lobster fishing) helps as much as one would think. It is definetly THE king for grip endurance, but all out crushing power is rarely needed.
As far as sets, reps, etc…that easily varies. Like anything else, prioritize it, and you’ll see your best gains. I like lower reps, and would rarely exceed 10 even with the #1. I feel closing the #2, and holding it as long as I could for a few sets helped a lot. I haven’t really fully prioritized it, I usually just seriously hit them on a day off, usually the day before legs. Try the Ironmind website, they have endless ideas.
I’m not just trying to plug Biotest, but Powerdrive always gives me an extra rep.
Anything else I can add, let me know.