I heard Bert Jansch being interviewed on the radio a while back by Liz Kershaw. Her son wants to learn guitar, so how should he start? Learn the piano, says Bert, then when he understands something about music, move on to guitar.
OK, but assuming you don't/can't do that, my own experience is that learning on your own is alright, but although I got pretty good at some scales, quite a lot of chords and chord progressions, and a number of finger picking patterns, it didn't really sound like music. This really became obvious when I went to an evening class, where 15 of us sat around and strummed. I had no sense of timing, which is pretty fundamental for playing with other people.
I'd say by all means teach yourself some chord shapes and practice moving between them until you don't have to think about it, but then get yourself a good teacher. And do yourself a favour - buy a decent guitar. Cheap ones can be hard to play and when you are learning that isn't what you need.
