Also known as trial and error (often mostly error!).
I'm self taught in that I received no formal training or education regarding the artistic or technical aspects of photography, however over the years I have had various mentors, attended a few conferences and workshops, and attempted to mimic certain things I was interested in, etc.
Part of any education involves exposure to the field of endeavor, so in that manner, I have received information and guidance from others. I don't believe there really is an opportunity to be self taught, unless you somehow invent and develop something from the ground up.
Self taught. I'm using the meaning as, "no formal education." I have read books, and I have run many rolls and sheets of film. Load, expose, develop, print, repeat.
While an educational course may open avenues for you such as teaching, I never wanted to learn how to photograph to teach photography. I became interested in photography because, as I was driving home one night, I became entranced by the moonlight on the landscape. It wasn't a grand landscape, it was just suburban-rural stuff. But that was the motivational spark. And then I bought a very used Pentax 6x7 and a 90mm leaf shutter lens, which is still going strong.
What is important to learning is remembering why I want to photograph things. I remember what I saw that first moonlit night. I remember when clouds lined up into a pagoda, with the moon in the center. I remember the morning when the rising sun painted a hillside in shades of red, bright to dim. I remember these things, and so I strive to continue with photography.
A bunch of both. Had a great high school instructor, then a great one at Junior College and what can you say about Cal Arts? Top notch. Then was an apprentice to 3 well known phtographers, mostly printing for them. That gave me a great foundation to build on. Funny how you either love photography or hate it. I love it