tavalla raises good points and you’d do good to heed that advice. Personnaly, i like a fast action (which i think is the same as tavalla’s ‘low action’), as i have less of a tendancy to inadvertently dampen other strings while chording. I don’t know whether you are looking for new or used so i’ll give you a bit on each:
New - Generally, you get what you pay for (although you can certainly pay more than you should). There are a lot of quality guitars being made, but only you can say which is the best for you. Martin guitars tend to be a little heavy on the bass whereas Taylor guitars are a bit more balanced. Some swear by Gibson, others by Guild. Yamaha, Takamine, Alvarez, and Sigma (a Martin company) also make good boxes. Look for a solid top, they resonate more and get better with age. Plywood tops are stronger and will stand up to abuse, changes in humidity, and travelling better. Strum a chord and then slide the same chord up 12 frets (one octave) a ‘D’ should still sound like a ‘D’ (you’ll be able to tell if it’s a little sharp or flat). Check the saddle and bridge; make sure the bridge is not loose in the saddle (no gaps), check whether the saddle is pulling away from the top (try to slide a piece of paper between the saddle and the top, you shouldn’t be able to), and make sure you have a ‘compensating’ bridge (the bridge should not be perpendicular to the strings but at a slight slant and there should be what looks like a ‘notch’ under the ‘G’ string). ‘Sight’ down the neck; hold the guitar up by the body with the neck parallel to the floor and at eye level pointing away from you. The frets should all appear parallel, if they don’t the neck is twisted and you don’t want to buy that guitar. Bow can be taken care of, but not twist. Look for signs of sloppy workmanship, glue that squeezed out of a joint and wasn’t cleaned up, rough frets, inlays not flush, etc. If there are mistakes that you can see, imagine what lurks in the places you can’t see. Be sure to look at the inside of the guitar also, there should be a label with the manufacturer’s name and (at least on the better guitars) a serial number. Although you may not be able to see them, ask whether the guitar has ‘scalloped’ braces for the top. These will also help the top to resonate. Ask questions, nearly every ‘decent’ guitar store that i have been in will have friendly and knowledgable help (if you’re lucky, it will be the owner). If the help is snotty (or snooty), walk out, they obviously don’t care enough to deserve your custom. Don’t pretend to know everything, but don’t pretend to know nothing, it just wastes their time. The guitars in a well run shop will have clean strings (no rust), they will be not far out of tune, will be either hanging or on stands, and will be obviously well taken care of. Also, don’t expect to be able to sit down with a guitar while wearing that big shiny belt buckle, they don’t like scratches. I make a habit of untucking my shirt before sitting down with someone else’s box, it shows that i care and they treat me better because of it. Personally, i like to frequent small shops and those that cater to bluegrass as it seems everybody there plays (and plays well).
Used - All the above holds with some exceptions. Don’t worry if the finish is crazed, it’s going to happen anyway. Any guitar that has been played will show signs of wear, expect the odd ding or scratch. On the other hand, walk away if the top or back is cracked, it’s generally not worth repairing unless it is a high-end guitar (which begs the question of why it was allowed to crack in the first place). Look for obvious signs of abuse. Take a set of strings with you if you are answering a newspaper ad as chances are you’ll need them. Get an idea of what a new guitar of the same model would cost to gauge your offer. Ask why it’s being sold.
More than anything else, play the damn thing. Strum some chord progressions, do some finger picking, run a few arpeggios, a little flat-picking, whatever. It has to sound right, and feel right. You wouldn’t think about it until you try it, but the neck of a Martin and the neck of a Taylor are two entirely different things. Try a lot of different guitars. I wouldn’t turn down a Martin, or a Gibson, or a Taylor, or a Yairi, or a Guild, but that doesn’t mean they are interchangeable. Each plays, feels and sounds different (even the same models by any maker). Unless you have the money to throw around, you’re only going to buy one so make sure it’s the ‘best of the bunch’ based on your own perception.
Lastly, buy the best guitar you can afford regardless of your ability. If you stick with it, your playing will improve to the point that you ‘fit’ your guitar. When i bought my first guitar i spent a lot of time hanging out in a small guitar shop. When i finally took the plunge, i planned on spending $500. The owner of the shop, knowing my ability (pitiful), helped me talk myself into paying $1313.25 for a Martin HD-28 (i still have the receipt) and i’ve never regretted it. I, at times, have not had the money for a pack of fags, but 16 years later, i still have my Herringbone D-28.
And i know she’s living there, and she loves me to this day. - Neil Young