A mechanical watch will keep more accurate time if it is kept consistently wound. When a watch is not moving it increases the likelihood that lubricants will solidify, which would increase friction in the movement. Beyond these basic steps, watch maintenance should be performed only by qualified professionals. Have your watches cleaned and lubricated every two to three years. Watches are easy to store and maintain, and raise only a few issues of upkeep.
Moisture can get into a watch through gaps in the case or through a break in the crystal.
If this happens, it can rust metal parts and severely damage the movement. Magnetism can ruin a mechanical watch. If some of the metal parts within your watch's movement become magnetized, it will disrupt their accuracy, perhaps irreversibly. Unless you have been properly trained, there is little you can do to repair your watch beyond searching for a trustworthy repair person. If you cannot send the watch back to the original manufacturer, ask reputable dealers or other vendors to suggest watch repair operations that they either use or recommend.