All you ever wanted to know about sound post adjustments, but were afraid to ask:
It is best to handle your instrument by the neck only. The natural oils from our skin attract dust and rosin to the varnish.
It is very important to keep the thumb leather near the frog of a bow in good condition.
Keep both your instrument and bow clean of dust, rosin, oils and dirt.
If the string slots in the bridge or top nut are too narrow, the strings will not slide through them during tuning. This can cause strings to break.