Choosing a guitar
Choosing a guitar is probably the most difficult thing to do. As a rule of thumb though stay away from Big Boxes such as Costco, the Bay, Walmart, etc. Yes you can save some money while shopping there, but you also may end up with a "lemon". Instead go to a music store where you will get help. A classical guitar has nylon strings and a larger fingerboard. Classical guitars and other types of guitars are made of real wood or laminated wood depending on how much you want to spend. There is nothing wrong with laminated wood, but don't expect the guitar to mature and get a better sound as it ages.
This is what you are looking for when buying a guitar:
Fingerboard is probably the most important part. It is important that the fingerboard should be straight. If it is warped, the strings will be too high and it won’t be possible to play the guitar. You can check the straightness of any fingerboard by using a metal straight edge and verify that the meter touches all the frets from 1 to 12. (See this video)
Size is also important especially for younger children guitars come in different lengths just like violon. Most common would be 1/4, 1/2, 3/4 and full size. On playabaleguitar.com you will find a chart that will help you choosing the right guitar for you. Use this chart as a reference only as many factors will play in choosing the right guitar for you.