All I can really recommend is listening to and playing your instrument very often. Another tip that can be helpful is to listen to notes played on violin by others and trying to guess which note is played. My friends and I often make a sort of game out of this, along with chords and scales. It truly helps a lot. Learning to recognize notes by ear doesn't come too quickly, and it can be harder for some. But if you keep trying, slowly but surely you'll be able to hear and name a note. Hope that helped. Keep playing and good luck!