Teaching yourself can be tough, but I personally think it can be more rewarding thatn having a teacher.
the first thing, I think, is to learn songs you really enjoy and know well, though they should be fairly simple, if you're just starting out. Don't take on some Vai, or Spiral architect if you're just beginning. I began with Gun's and Roses, simple folkish strumming stuff, and Slayer. Looking back, I realize why I could never play the Slayer stuff very good at first...
Practice open chords, it'll stretch your hands, and since you usually change chords fairly slowly, it's a good way to start. Try to get a feel for strumming different rhythms, and later, try and arpeggiate the chord patterns, picking certain notes in the chords instead of strumming them all. To get a feel for your guitar, try closing your eyes, then place a left hand finger on a random fret, then try to hit that string with your pick, with your eyes still closed. I found this to be particularly helpful in getting used to the feel of the guitar, it's string spacing, and so on.
Finally, wherever you are, with a guitar or not, practice! That's how I learned the solo's in "November Rain" by Guns and Roses. I'd sit in class at high school, and pretend I was playing my guitar, just visualizing the frets I had to hit, and moving my fingers along with the solo in my mind. Train yourself mentally as much as you do physically. And listen carefully to your music. Once you get a really good feel for distinguishing rhythms of different instruments in a piece of music, the ability to physically play the piece will come much easier.
Now there are a few, very random ideas I pulled from my own experience. Hope they can help to some degree. Good luck with the guitaring!