Dampen a cloth or a paper towel and add a few drops of your favorite dish detergent or liquid hand soap.
Gently rub each leaf of your plant with the soapy cloth or paper towel. Rub between your thumb and first finger so that you are rubbing both sides of the leaf at the same time with a slight circular motion. Use very light pressure. Unless the leaf is coated in sticky grime (such as might happen if the artificial plant is in the kitchen where it could become coated with air-borne cooking grease), each leaf should take no more than a couple of seconds to clean.
Rinse the cloth out or dampen a new paper towel and rub each leaf a second time with plain water to wipe off the soap. Allow the leaves to air dry.