The first step in cleaning a carpet stain is to determine the stain's cause. It's also necessary to determine whether the carpet is made from a synthetic or natural fiber before cleaning, according to Real Simple.
Oily and greasy stains include butter and salad dressing as well as lotion, crayons, tree sap and many cosmetics, such as mascara and nail polish. Real Simple recommends applying a small amount of solvent to a white cloth to remove these stains from synthetic carpets. Dab the cloth repeatedly onto the stain, and then press the cloth onto the stain for several seconds. Rinse the area by blotting it with a white cloth soaked in lukewarm water. Wait about an hour or until the area is completely dry. If the stain is becoming lighter, repeat the cleaning procedure until the stain is gone.
To remove oily, greasy stains from natural fiber rugs, apply a small amount of solvent to a white cloth, and blot the stain. Real Simple advises spraying a solution of detergent and water onto the stain. Blot the stain with a dry white cloth, and then spray the area with lukewarm water. Blot again with a dry white cloth. If the stain is lighter, repeat until the stain is removed.