While there are numerous free resources online, mastering the necessary postures and techniques of the violin is difficult without proper guidance. Especially when learning bowing and fingering techniques, incorrect postures can easily develop. Once these "bad" habits are established, they become hard to correct later on.
Compared to self-study, one-on-one guidance from a professional violin teacher is undoubtedly more effective. A private violin teacher can not only promptly correct a student's mistakes but can also teach music theory, reading music scores, and share examination and performance experiences. The knowledge gained from a violin teacher goes beyond the depth that self-study can achieve.