Not to hijack this thread, but to be clear I agree completely with Racer that starting most people off with scales and deep theory is totally offputting. That is what killed piano for me. But I am someone who played amateur guitar for 20 years, reading TAB all the time, had all the nice fingering, could do an F chord quite happily, and strummed along, and never got anywhere because there was no cumulative learning -- I knew there was more going on in "BIG MUSIC", but that all pop and folk songs had a structure that made it pretty likely that Xchord followed Y chord a lot of the time was actually a revelation! And that choruses shifted very often predictably, etc. People don't know any of this stuff anymore.

A half an hour with theory, at the right moment, and it all fell into place for me. That is all I am saying. People don't even know that a 7th chord is the secret to getting to the tonic. Why does a G7 show up so often in songs that start in C? I mean really basic stuff. Incredibly helpful.

yours, Peter T.