/me loves his guitar(s).
I’ve been at it for about six years now, and doubt I’ll ever be able to stop. I’m in three bands (only guitarist in all of them) as well as the school Jazz Band, and practice daily. I’ve got loads o’ tips for anyone just starting out; here’re a few:
How you approach the guitar, what you practice, etc., all depends on what sort of music you want to play. If all you want to do is cover songs of your favorite classic rock musicians, then it’s a great idea to learn to read tab, brush up on basic barre chords (minor, major, 7th, etc.), and learn your basic scales (again, minor, major, possibly the modes, etc.). If you want to play metal (especially if you want to write your own stuff and have it sound great, or play very fast/technical/advanced songs), you have to get a lot more technical, especially in terms of lead playing; learn approximately the same amount of chords (you can always look up more advanced ones you come across, and there won’t be that many; unless, that is, you plan on using a lot of arpeggios, in which case you should learn all the chords you possibly can), but practice switching quickly from chord to chord and playing them in all possible different places on the fretboard, and go nuts on your lead playing; practice your minor, major, modal, harmonic minor, melodic minor, etc., scales as often as possible, in all possible positions on the fretboard. Also, doing guitar exercises to improve your speed (there are some good ones at www.guitarists.net) daily will work wonders. Pretty soon, you’ll be able to rip it with the best of them. If you want to get really far out there, learn more obscure/advanced playing techniques like tapping or sweep picking, which will allow you to play faster and get more unique sounds out of your guitar. Learning music theory, especially that relating to rhythm (many metal songs utilize obscure time signatures and odd bar divisions), will help a good deal too. If you’re looking to play jazz, you have to get in even deeper; learn chord theory and program it into your fingers to the point where you can figure out on the spot how to play an Ab5#11+7, and cover every section of music theory from harmony to modality until you’re well-versed in all of them. Then, learn to sightread sheet music and be able to analyze which chords are behind each part of the piece you’re playing, so you can successfully improvise over it. At this point, your chops will probably already be brilliant, so you’re free to go and join an ensemble.
If you don’t want to take lessons to learn these things, you may have a bit of a harder time getting the ropes at first; but if you look around on the internet and swing by a music store or two, you can probably find enough websites, books, and videos to get by quite well with. Also, feel free to PM me if you have any questions.
Being a skilled guitarist takes a lot of work and commitment, no matter what you plan on doing with your skills–but it’s also intensely rewarding. The guitar is one of the best creative outlets I’ve found for myself, and the thrill one gets from crafting a really wicked song or playing a shimmering solo is almost unmatched by anything else I’ve found in the world.
Good luck, and may your interest in musicianship never wane! 
I play solos mostly and I also sing.
