I get many Emails and phone calls from people who want to know how to find a guitar for a beginner. The good news is that you don't need to spent a lot of money for a student-model guitar. As little as $100 to$200 will work. The guitar is one of the few instruments where you can buy a beginner's instrument so cheaply. If the student wants to keep on studying, then it will be important to upgrade.
There are two different styles of guitars. One is the classical guitar, and the other is the steel-stringed guitar. The difference between classical and steel-stringed guitars is easy to see. The fingerboard is a lot wider on the classical, and its body is slightly smaller than the steel-stringed guitar. Its strings are made of nylon, so they're softer and easier on the fingers. The classical guitar's sound is much mellower, and is good if you want to play classical or folk music. A steel-stringed guitar is best for playing rock, country, and pop.
Steel strings take some getting used to, because they are heavier, and made of a sharp wire that slightly digs into your finger tips. The tips of your fingers will get calluses over time, so the strings will feel more comfortable. The good news however, is that on a steel-stringed guitar, you can buy extra light steel strings, and that makes it easier on the fingers, but not as easy as nylon strings.
Over all, I prefer the classical guitar for the beginner because nylon strings are easier on the fingers. Later if the student wants to go to a steel string guitar, that will be fine because their hands will be stronger and more used to the guitar. However, I don't require a beginner to get a classical, nylon-string guitar. This is only my suggestion. Some beginners have their heart set on a steel-stringed guitar, because they like rock or country music.
One thing you must never do is to put steel strings onto a classical guitar, even temporarily. The two types of guitar are designed differently. The classical guitar has lighter wood, so the steel strings' higher tension will warp the instrument, very quickly making it unplayable! Even if this weren't a concern, steel strings on a classical guitar sounds totally wrong anyway.
As strange as it may sound, it's also important to make sure that what you buy really is a classical or traditional steel-stringed guitar. There are also similar-looking instruments, often in the same racks at the music store. Beginners need to avoid 12-stringed guitars, dobros, "steel" guitars (not to be confused with "steel-stringed" guitars), slide dobros, tenor ukeleles, acoustic bass guitars, and a few other more-rare instruments. You can avoid most of these by other instruments by making sure that it has exactly 6 strings and an entirely-wood top, excluding a pick guard. Steel-stringed guitars have a plastic pick guard attached to the wood top, below the tone hole. That helps protect the wood from scratching from the pick. Classical guitars don't have these because you don't use a pick on a classical guitar.
Steel-stringed guitars can also be electric. I don't recommend electric guitars for beginners, because they're too easy to play! You don't have to touch down on the strings as hard. That may sound like a positive thing, but it's not, because if you change to a classical or a acoustic steel-stringed guitar then your fingers won't be strong enough. So, too easy is no better than too difficult! If you do nevertheless decide to work with me on an electric guitar, please plan on taking a miniature amp with you to your lessons.
Don't buy a used guitar, unless you hire an experienced and independent guitar teacher or guitar-repair technician to check it for you. You could easily end up with a piece of junk and spend more money on repairs. Another thing I've often seen is that a beginner would come in with a family member's very old guitar. The tuning pegs are often rusted and don't work properly, and often the strings are put on backwards. I've seen this all too often. A new guitar is best for a student, and they will have a pleasant experience with music without any hassles from an old guitar can bring.
I want my students to be happy. But, I hope they'll stay happy when their fingers hurt a bit! I hope this helps. Any further questions, pleas call or email me.