Purchase a violin that is the correct size for the child who will be learning. For young children under 12 years of age, you should purchase a half size violin from a reputable dealer. That way the violin can become a trade-in when the violin is too small for the player. In most cases, you can expect to pay between $500 and $1,500 (based on 2010 prices) for a decent student-quality violin, though there are rental options available from many music stores.
Learn the notes on the violin. Purchasing a finger note guide that will fit onto the violin's fingerboard is a great way for a new player to memorize the positions of the notes, which can be exceedingly difficult when you first start playing. Make sure you get a guide that will not leave any sticky residue on your violin fingerboard, especially if you are using a rental or good-quality violin. Remove the finger note guide as soon as possible so that it does not become an unnecessary crutch when playing.
Learn to tune the violin properly. On a violin, the strings are tuned G, D, A, E in standard tuning. An electronic tuner or reference keyboard is an essential tool for a beginning player, as it will help to teach the proper pitch. Proper tuning is extremely important when starting out, as you will be learning how your violin is supposed to sound while you are playing.
Learn to read sheet music with relative ease. Learning to read sheet music can be a difficult task, but it is essential if you want to progress past the beginning level as a player. There are many wonderful books that can assist in learning to read music, including "How to Read Music: Fundamentals of Music Notation Made Easy" by Roger Evans and "How to Read Music" by Leonard Vogler.
Practice for at least one hour per day when starting out. It may seem like a cliché, but in most cases, practice really does make perfect. Much of learning to play the violin is about finger strength, muscle memory and repetition, so regular practice is a must in order to advance to the next level.