Really you need to hold it,play it, inspect it,listen to it. The top of the violin should be made of spruce, the ribs and back maple. The fibers or”lines in the spruce should be fairly close together. The maple should have visible stripes. The varnish on fairly new violins can fool you because many of them are made to look like the old Italian violins.
But more important than the way it looks is the way it sounds and they way it feels in your hands. Some instruments just fit me better than others. Aside from the sound of the instrument when you play it or someone else plays it, it has to be comfortable in your hands and easy for you to play, There are violins that I have tried that make me play better and some that make me play worse. Generally speaking if I can afford the ones that make me play better I buy them. For me playability, and sound is more important than looks. I own an old German commercial fiddler that looks awful. It’s dented and has repaired cracks in it but it sounds great and I love it. I have a Chinese violin with no label in it that I picked up for $200 to play in bars that sounds pretty good and looks excellent….. Just my 2 cents, and first post