it up and have the instrument fall out.
do not lay an instrument down half-in and half-out of a case. the case lid can fall down and damage the instrument. if you put an instrument down, the best place for it is fully inside of a case with the lid open, or inside of a closed and latched case.
do not leave your instrument in a hot or cold car or trunk. extreme temperature changes can cause cracks in the wood. heat can cause damage to the varnish.
do not pull broken hairs out of your bow. pulling a hair out of the frog or tip ends of the bow can loosen more 