If you are buying a violin for the first time, you need to bear certain tips in mind so that you do not end up with a defective piece or a violin that you do not really feel comfortable playing.
If possible, go along with your teacher to buy a violin so that he/she can judge the kind of instrument that will be perfect for you. Violins come in different sizes and quality. There are various manufacturers of violin like Italian, Indian, Chinese or German model. Get to know which manufacturers provide top quality instruments. Get the names of reputed violin manufacturers and shops selling those pieces.
Go to the shop personally to buy it. Do not just let your parents or teacher buy it for you. You need to position the violin the way you hold it and check out if you feel comfortable holding it. See if the piece fits your size.
If you are considering buying a second hand or rented violin, inspect it thoroughly for signs of damage or breakage. Do not take the violin, if it is discoloured near the strings and neck. If the violin is too old, it will need special care and maintenance.
Check the bridge of the violin. It should be standing erect and should not be leaning in front or backward. Check the tuning pegs. They should not be very rigid. Check the strings and see to it that they do not cut or scratch your finger when you slide it over the strings.
Choose a bow that fits your size so that you do not feel uncomfortable while bowing.
You can also choose the colour and finishing for your violin. Also listen to the tunes the violins produce. Hear out some violins and choose a piece that you feel produces the sound you like best.