Dry fire is useful for any gun; some need snap caps to avoid damage, but proper dry fire is always good. It's also free.
I'm not going to argue with Jerry Miculek, even if I don't personally put my supporting thumb over the back of my firing hand. I mostly shoot semi-autos, and personally just don't want the habit pattern ingrained.
Some J-frames are harder to shoot than other J-frames. Of my two 442s, the one I took in trade, LNIB, had a great trigger. The one I bought, NIB, had a 15lb trigger - heavy, but at least smooth. I installed an APEX kit, and now it has a 9lb, still smooth trigger and it is much easier to shoot.
I may have missed it, if somebody already said this, but changing grips can also help. I have fairly large hands, and the old-school J-frame grips don't cut it. I need a Tyler T adapter with those. The new grips that come on the 442 work ok; rubber with palm swell and finger groove. I just bought some slightly oversized Altamonts, since I like wood, but haven't had a chance to try them yet.
It's hard to shoot a gun you can't get a grip on.