The only thing I can add to the excellent responses already is to not store them fully closed. Leave them open perhaps.015 for storage.
Temperature changes will cause the metal to expand and contract thus putting stress on the gears (threads of micrometers) and slop will develop. Leading to accuracy issues and wearing them out prematurely. This is not as big an issue with calipers as it is with micrometers but it sure doesn’t hurt anything to treat your tools with the most care possible.