The best thing to extend the life of tubs is to use non abrasive cleaners designed for the purpose. Whether the tub has an acrylic, gel coat, marble, paint or enamel surface, it can benefit from waxing from time to time. About every fourth cleaning, use gel gloss or any automotive wax that contains a silicone sealant. Do this for the same reason cars are waxed. If bathmats are not used, avoid waxing the bottom area. If using rubber mats with the suction cups, lift them off after using the tub. Permanently having the suction cups attached can cause damage over time. Not to mention the unhygienic build up of dirt and bacteria under the mats.