haha an explanation with words wouldn't really help much since its hard to explain... and your explanation might cause confusion like "the pinky should be down and the ring and middle finger should be over the bow. The index finger is wrapped around the bow." The image that this conjurs up would pretty much be wrong It needs to be SEEN in RL
"the fingers should be curled so the tips of the fingers are touching the strings" there's a certain way that you need to do that, the fingers are curled, pointing to the direction of the "bridge" ^ ^" Something I got lectured about in my master class last week.
For a few pose and violin tips: There should be a chin rest on which she rests her jawbone. That is too big to be a violin, it is more along the lines of a viola. She would be using all five fingers to hold onto the bow, or it would be swerving all over the place. Her arm would be about the same level as her hand, or else there would be no pressure on the strings, and the neck seems just a tad too long. You also forgot the F hole on one side.
Sorry, I hope that didn't seem too harsh. I'm sure you've improved from when you drew this. It really is a lovely picture though.