Jungling: Need Guidance

I started as a top main, and was the model of consistency there. I'm now a support main, am just as reliable there, and my champion pool there is far more diverse than it ever was for top. I have a set of mid laners I can, at the very least, hold my own and contribute with in the rare event I need to go there. And, given I almost never have to ADC in ranked (3 times on my first account, EkkoFroffles, all season), and that I know I'm not mechanically sound enough to excel at it, I'm not worried about that role at all.

That just leaves jungle, a role I'm boom or bust in. If I have a weak start, the chances of me coming back for it are slim because I only seem to do well when I get rolling and build up some confidence. I want to fix that. My plan is to approach it how I did supporting when I switched, Level 5ing one jungler after another, playing jungle almost exclusively. But any guidance to help me out along the way would be greatly appreciated.

Thus far, I've had success with Ekko, Wukong, Amumu, Sejuani, and Vi (though I don't own the last two yet on this account). And I own these other junglers currently: Cho'Gath, Fiddlesticks, Kayle, Maokai, Malphite, Master Yi, Nautilus, Nunu, Tahm Kench, and Warwick.

Mostly, I want pointers for a couple things: dealing with counterjunglers and coming back from behind. But any help at all, be it through advice or videos, will be greatly appreciated.

My goal is to be as confident jungling as I am top and support, even if I never get to be as good at it as I am with those two roles.