The positioning of your arm will vary for each string. Each string has its own string level that your arm aligns to as you play on that string. Your arm will be highest on the A string and lowest on the C string.
There is a simple exercise to find the best positioning for you:
- Hold the bow in your hand as you would for pizzicato.
- Bring your hand to the string where you will use the bow.
- Pluck the string and then immediately ready your bow to play.
Do this for each string. Observe how your arm is positioned differently for each string. Repeat the exercise again, but this time add in these steps:
Draw the bow to the tip. Be sure to keep the bow parallel to the bridge and fingerboard. Hold the upper part of the bow with your left hand.
Move your right hand up and down the bow as if you were playing. Your hand should be in up-bow position when moving toward the tip and down-bow position when moving toward the frog.
The position of the bow is the string level, and observe the alignment of your arm as you move your hand up and down the bow.