When holding the violin in the playing position, straighten your left arm and the tops of your fingertips should be near the top the violin scroll. If your arm is way past the top, the violin is too small. Buy from a reputable seller. Music stores stake their reputations on selling solid instruments that are free of obvious flaws and damage. As a beginner, you won't be able to coax a very pleasant sound from your instrument for some time, so flaws in privately sold violins might not be apparent to you until it is far too late to complain. Only buy from a store or individual you can trust.
