Wash with mild soapy solution at least once a year removing mold, mildew and dirt. Rinse thoroughly to remove all of the detergent.
Place sculptures in a protected area where rain, snow, hail and wind won't damage it as badly. A simple wall to block winds or placing the sculpture in a picnic shelter keeps weather damage to a minimum.
Move terracotta sculptures into a sheltered environment during the winter. They can crack from the extremes of heat and cold temperatures.
Apply protective coatings to specific types of sculpture. Painted ceramic, cement or wooden sculptures should be cleaned, allowed to dry and then resealed each year. Any damage to the paint should be touched up with acrylic paint and allowed to dry before sealing with three layers of clear spray paint. Allow the spray paint one hour of drying time between layers.
Clean metal sculptures with mild soapy solution once a year and coat with microcrystalline paste wax to repel water and to preserve the metal.
Place outdoor sculpture away from trees and plants with vines. Sap and animal feces damage sculpted surfaces. Vines attach to the statue and eat away surface coverings causing erosion.
Repair nicks in wooden sculptures with wood putty and sand it smooth after it dries. Match the paint color, paint it on and seal with clear spray paint or Microcrystalline paste wax.
Donate the sculpture to a local museum, and let them keep up the repairs if the piece is a historical piece for the area. Many museums keep local paintings, sculpture and crafts in a special area of the museum accenting the area's local artists.