Store your table saw in an appropriate place. Find a place where the saw will not come in contact with moisture, which is the leading cause of rust on metal. Keep a tool box in a dry closet, on a storage shelf or in a drawer.
Spray the surface of the table saw with a lubricant oil like WD-40, then take an abrasive pad and scrub the saw down. This will help to remove any rust that is already on the saw as well as coating the saw for protection from future rust damage.
Wipe vinegar over the saw's surface. The acid in the vinegar will help prevent rust.
Continue using a cloth sprayed with lubricant oil periodically, not only to prevent rust but to keep the saw working properly.