All of the above will help you make a more qualified decision when it comes to purchasing
your second hand Acoustic guitar but if you are a novice still and not sure how to check thoroughly or if it sounds a little complicated for you then it would be really advisable to take a friend with you who knows about these Acoustic guitars and is very experienced in playing them, take their advice, listen to what they say, even if you absolutely love the look of a guitar, do not buy it on looks alone, always listen to the best advice.