Never leave the case unlatched.
Carry the cello so that the neck rests on your right shoulder and the bridge faces to the left.
Never store a string instrument in direct sunlight, on top of a radiator, near a heat register, or in extreme cold places. This will prevent cracking the wood.
Always loosen the bow after playing.
It's a good idea to carry an extra set of strings in your case, should there be an emergency (especially Violins and Violas).
A very soft piece of cloth should be kept in the case. After playing session, the rosin should be wiped out off the instrument and strings.
When rosin has caked on the strings, use a clean soft cloth(one that you won't mind getting dirty) and small amount of rubbing alcohol to wipe the strings. Be sure that none of the alcohol drips on the body of your instrument. This could strip the varnish from the instrument.
Make sure that both ends of the bow are put in their proper place in the violin/viola case.
Do not store music in the case. Although it may appear to fit, it will eventually place a strain on the instrument and case, resulting in costly repairs.
Be careful not to bang or jar the instrument. A case serves as an aid in carrying the instrument and is not infallible protection for that content.
Special care should be taken to see that the end pin is retracted on the cello when not in use. the cello bow should be taken from the case before taking the instrument out. When putting the instrument away, the bow will be placed last.
Polish the wood portion of your instrument a least once a year with string instrument polish. DO NOT USE FURNITURE POLISH.
Do not leave your instrument lying around - EVER - on anything! If you are not using it, put it in the case and latch it.
Cellos and basses should never be laid to rest on their backs. If necessary, rest it on it's side.