I've been asked to share my personal history and training as a minis painter from time to time, so I've decided to put the story here. It is just a little long for a forum post.
I got into minis 16 or 17 years ago when I was eleven. I actually started out painting Monster in my Pockets, some Space Crusade minis and some old Ral Partha D&D characters.
For many years I was awful. I mean, really bad. Now, as an eleven year old, I was convinced that my stuff rivaled the 'eavy metal studio paint jobs.
The biggest problem I had for many years was trying new techniques. I learned to ink, guide coat and dry brush and for a long time I thought that other techniques were too complex, and that I should try them out "when I get better."
Sometime later- when I was 22, I realized that there was simply no reason I couldn't paint as well as I wanted to. So I tried out a bunch of new techniques, and my painting shot up.
After that, I actively strove to find techniques that intimidated me. I've actually chosen factions to play because I was intimidated by the painting. I often look up tutorials online or in magazines, and I try to take ideas from some of the painters I idolize.
Currently, I am as good as some of the painters I used to idolize, and I'm striving to be as good as the ones I think are awesome now.
So, no formal training at all. I did not major in visual arts in college, or even take many art classes in high school. I just started trying new things, and decided that there was no limit on how good a painter I could be.
So, the great secret is to try out something that you don't think you can do. You will always learn something, even if you don't pull it off the first time. That's how you get to be a better painter.