I picked up a guitar one day and I didn't know how to tune it, so I spent a long time figuring out the spacing of the notes on the High E string (whole steps and half steps and all that).
Then I went on to the other strings just like that. Then I started to see certain patterns and finally started learning some chords. After about 2 1/2 years of playing none stop I finally took lessons from the most unlikely source - a bluegrass musician. Man did I learn a lot from that guy.
I'm never finished learning how to play guitar though. I discover new things every day - I love this stuff
