I'm finishing up teaching guitar this week after doing it for nine years.
I haven't read all the thread but the few posts I've read hit the target.
Get a cheap acoustic. Nylon strings are easier but the neck is wider. Steel string acoustics have a narrower neck but a cheap one can be a bitch on your fingers. That said, it will toughen your fingers and strengthen your hands the most.
If you want to be self taught (I was for my first year) get a book. Some youtube stuff can be hit and miss, whereas books are generally better IMO as they are more comprehensive and the lessons are set out in a way that build basic skills and expand upon those into the later lessons. Books these days almost always come with CDs so you can play along to the backing tracks (very useful for listening how the song is meant to sound and making sure you're playing in time - I can't stress enough how important learning to play in time is) and many also come with DVDs so you have the backing tracks and video examples to follow so you can see how to use correct technique. Books are also cheaper than lessons but you need to be committed and practice daily (minimum is half an hour) to constantly improce.
If you take lessons try to either seek out a music school, ask at a music store (like where you would buy your guitar) or ask a friend who has had lessons if their teacher was good. The advantage with lessons is a good teacher can really pick up and hone in on correct technique and troubleshoot any tough parts you come to that you can't seem to figure out. Having a teacher can also be a bit of a motivator as you have someone there to help keep you in check, and the added financial cost is an incentive to some.
Learning guitar can sometimes be a frustrating experience, but a rewarding one. It does take years of consistent playing to get to a level where you can pick one up and play stuff by ear off the top of your head (ie. improvising or just figuring shit out without much effort), but to play most songs you would hear on the radio involves learning all your open chords and the four primary bar chord shapes (E and A formation bar chords and their minor counterparts) and won't take you years to get that much down, maybe 6-12 months to learn those chords to a point they aren't a struggle and you can make the song sound decent.
You don't need to know a lot of music theory but learning the basics is almost essential IMO, and not really that hard.
Last edited by Jaekus (2012-03-26 06:22:59)