1. The age and readiness of your child. I recommend pianists be at least 4 years old and string players be at least 6. All budding musicians should know the alphabet through G, the difference between left and right, numbers through 10, and preferably, how to read simple sentences. 2. You need an instrument. I very much enjoy helping my students procure an instrument for studies, so I'm happy to help explain the process to you and make recommendations according to your budget.