If your a beginner and you're thinking about buying a second hand guitar here are a few things to look out for.
Check for the following while looking the guitar over.
Small scratches or grazes shouldn't cause a problem but they should be reflected in the asking price of the guitar.
Make sure that there is no cracking present where the neck of the guitar joins the body and that the neck isn't warped or twisted.
Check the distance between strings and the last fret (nearest the body of the guitar). The strings should be as close as possible to the fret without actually touching it or causing the strings to "buzz" when played. The higher the strings from the fret the more pressure is needed by the fingers causing pain and soreness and making the sound distorted.
If all seems OK go ahead and make your purchase. If in doubt try to go back and look again with someone who is experienced with guitars.