I cant tell you the 'best' way to learn...but i can tell you what i did.
i read alot at first, on this board and others, about where to go, what to keep in mind, what you need to pre-check, post-check, what tires to buy, what i could do in stock trim, what i needed to mod for the next level, all those things. i also began checking websites like
https://expeditionportal.com/ which talk extensively about off-roading and overlanding. then of course there are several yootuuub'rs out there to give you pointers, lessons, mini classes from the USA, Aussie, and other places where it has a particular lifestyle set.
and then, i just found places to go, where i could get started with and without the aura of embarrassment. I mean, when doing anything new, everybody has to start somewhere...everybody has to be 'The Newbie' at some point...so just go in and get started. Talk to and listen to those who know, learn from them, and get your own tires dirty. Find those places you are allowed to go, and even find some places where you can sneak in a few miles here and there. Soon enough, you'll have some experience with those things that you need to know about...when and how to shift into 4H...when and how to shift into 4L, how to use momentum, how to drive with both feet, picking lines, gauging distance, being wow'd by what your truck can do vs what your bravery is willing to try, etc.
and maybe most importantly, dont overthink it. just get out there, take small steps, and DO-IT...before long, you'll be having the fun that a T4R is made for.