Mmm school trained? I started as a self taught, but then I took some courses in drawing and painting in the nearest community centre and I study grahic design so I took one elective in ilustration, but I didn't learnt too much, and a basic course in general art, where they taught me about color theory and all that stuff that I forget sometimes.
I can say I have a school background as good as someone that went to a high school with a decent art program.
What helped me to be more decent in art , was the book You can draw in 30 days from, it took me a year almost lol... yeah I am a slow learner. That gave enough courage to try to study something in grahic design, but after the elective in illustration I realized that drawing can always be a hobby, lol.
And I also started all that after finishing college when I took my first job, just to releax, but I ended up liking it a little too much lol...