Place mats in areas that see a lot of traffic (such as entrances and exits) or moisture (such as bathrooms and laundry rooms). Furniture pads are also a good idea. Dragging large things like couches or pool tables could cause serious damage to tile surfaces.
Regular sweeping and dust mopping will prevent surface scratches. You can do a deeper clean with a damp mop and a floor cleaning solution that isn’t acidic, abrasive, or bleach. 
Porcelain tiles are very durable and resilient. They don’t need to be reglazed or refinished. However, you may have to reseal the grout depending on how porous it is and where it is. Stone tiles, however, are extremely porous and need to be resealed on a regular basis.