So, to the question at hand:
I learned from reloading manuals and books and from a few local reloaders. I did everything basically as hard as you could make it when I first started out.
Then when I started competitive benchrest, I picked up a lot of new tricks to improve the precision of my ammo and the life of my brass from other shooters.
And of course, some time in the late 1990's or early 2000's I found that the internet is a great place to learn, as well as a great place to hear a lot of BS that will just waste your time at the bench.