Before we dive into the advice, let me be perfectly clear. I'm talking about steel-string, wood-body acoustic guitars. Not pedal steel, archtop, classical, or electric. Even if you're interested in a different kind of guitar, the advice below is probably applicable with the appropriate substitutions. Personally, though, I'd recommend starting with an acoustic steel over any other guitar—they're the most musically versatile, and you don't have to plug 'em in. Moving on...
Part 1: Buy a guitar.
Buying a guitar is kind of like buying a boob job. You have to think about your motivation and commitment before you jump in. If you're buying a guitar to impress people, you're going to wind up with an expensive monstrosity that sits in the dark. You're just starting out, so don't expect to get anything fantastic. Really, you can spend as much or as little as you want. Decide your price range and don't let a salesman move you out of it.
If you're really unsure about whether the guitar is your thing, or if you're really strapped for cash, then expect to pay about $50-100 and expect it to sound pretty crappy. You can get a better one later. At this level brand doesn't really matter. For now just grab the cheapest one and go for it. Of course, if you have several options at the bottom of the ladder, mess with them all and get the one you like.
If you're really excited and you have the bucks, then expect to pay $200-500. You have much more variety at this price range, so shop around a lot. Don't go to just one store, and try out everything—all brands, all models, all prices. It's very easy to be intimidated at this point. Don't be! Just mess around and be open about the fact that you have no clue what you're doing. Pick stuff up and make noise with it (use your fingertips to pluck and the backs of your fingernails to strum), or have the salespeople play them for you. Go for the one that sounds best to you. Options you may wish to look for in this price range are a solid wood top (as opposed to laminate; it'll sound better) and a pickup. If you want a brand recommendation, go for Takamine guitars in this price range, especially if you want a pickup. But remember, the most important criterion is how it sounds to you.
Really, you shouldn't spend more than $400-500 unless you don't mind wasting money. More expensive guitars vary a lot in quality, nuance, and feel, and you just don't know what to look for at this point. If you feel like you want a swank guitar, then get a dirt cheap one and play it for a few months first. Once you know the ropes you can make an informed decision. Trust me.
By the way, the strings on your guitar make quite a bit of difference in terms of sound and playability. Do not keep the strings that were on the guitar in the shop. They're probably poor quality, grimy, and worn out.
String brands and styles aren't much "better" than one another; they're just different. If you're bewildered, just pick one at random. Do stick with light strings at this point. Have the shop put them on for you, and watch them do it. Change the strings every month if you play regularly, or every week if you can afford it and want to try different styles.
Other goodies you might want but can certainly do without:
You can probably talk the shop into throwing some of this stuff in for free. The most common freebies are picks and a gig bag.
- a string winder
- a thumb pick (make sure it fits!)
- a strap
- a case or gig bag
- a tuning fork (if you have a good ear) or an electronic tuner (for the rest of us)
- a floor stand
- a capo
Part 2: Learn to play it.
Now you need to find a teacher. It's really important to pick the right teacher for your interests and personality. Call around to guitar shops and ask them who to talk to. Meet prospective teachers face to face. Do you like them personally? Will they put you in touch with other students of theirs? Do they charge a reasonable price? Do they teach styles of music that you're interested in? Shop around for teachers just like you shopped around for your guitar. Remember, the effort is worth it!
Note that you will have an easier time finding a teacher if you're willing to learn different styles of music to begin with. In my experience, crusty old people are often the best teachers. Most crusty old people do not play Creed and Staind. A little Woody Guthrie never killed anyone. Also note that the teacher may not like your guitar. Guitar players are, like other craftsmen, opinionated as all hell. You chose the guitar that you could afford and that you liked. If they can't deal with that then find a teacher who's less arrogant. I've heard teachers say that they turned a student away because their guitar wasn't good enough. That's crap!
Aside from finding a good teacher, you have to practice. This is the part that causes most people to give up. You don't have to sit down for an hour a day and play scales and I-IV-V-I over and over. Keep the guitar close to you at home and just fool with it whenever you get a chance. Don't neglect the exercises your teacher gives you, but don't spend all your time slaving either. Play around! Noodle! If you play for a few hours a week, you'll improve pretty quickly.
After you know the basics, you can try buying some songbooks by your favorite bands. Show them to your teacher and have her walk you through them. If there are specific techniques you want to learn, find a recording of them and play it for your teacher. But as a beginner, use your teacher as a primary resource—that's what you pay her for. Once you know styles, idioms, and techniques, books are good for learning new data. Until then, books can actually do you more harm than good. For example, if you look up the tablature for an F#m barre chord but don't know how to place your index finger, you might develop a bad habit that's hard to correct. Good habits are crucial to good playing, and only a good teacher can provide them.
On the off chance that paying for your guitar sapped all of your lesson funds, Cyberfret has a lot of good entry-level and all-around good guitar information, and has photos of the techniques that are easily screwed up. Guitar Man's Acoustic Guitar Tips are a good source of random trivia including some great care and maintenance info. Last but not least is the rec.music.makers.guitar.acoustic FAQ.
If you follow the above advice to get started and if you stick with your guitar, you'll be pounding out songs in a few months. The first few weeks will be painful (as you develop calluses) and annoying (since you can't actually play anything yet), but hey. The worst that can happen to you is a bit of burnt cash. On the other hand, if you're lucky, you'll become addicted and absorbed for years to come.