1)Wet a sponge in soapy water. Completely clean your wood outdoor furniture of dirt, tree sap and other grime that has built up. Rinse the furniture well with a garden hose and let it air dry. Pollution, bird droppings, tree sap and other substances will stain patio furniture if they aren't cleaned off.
2)Spread a waterproofing wax or gel over the furniture using clean cloths. Make sure the wood is fully dry first and that the waterproofing formula is specifically made for wood. For most products, apply the waterproofing formula to a cloth first and then rub it into the wood one section at a time. (Wear gloves for this process.)
3)Use patio furniture covers over wood furniture during rainy weather. Even after you have waterproofed the furniture, this is an important step for protecting the wood from excess moisture. Furniture covers come in several different sizes and are very easy to use.
4)Keep the furniture covered and store it in a garage or shed at the end of the season. If you are able to store it inside your home, this may be even better since a home is climate controlled. (Storing patio furniture indoors is especially important if you live in a region with harsh winters.) If you do not have room in your home to store the furniture, a garage or shed is the next best thing. These will at least protect the furniture from driving winds and rain, sleet and snow.
Other tips:
a)Check screws and other furniture hardware occasionally. Some may loosen or even need to be replaced.
b)Do not allow children to jump or play on wood patio furniture. It is dangerous both for the furniture and the children.
c)Avoid storing wood furniture in damp rooms, such as basements. Mildew may develop on the wood.
