Draw enough lukewarm water in a large pan or bowl to cover the wig or hairpiece well. Dissolve a capful of prescribed wig shampoo, along with 1 tablespoon of baking soda. Swish wig or hairpiece around, squeezing hair gently. Keep hair moving in one direction or it may tangle. If front of cap has makeup on it, it may be scrubbed gently.
Rinse wig well with plenty of lukewarm water.
Dissolve a capful or so of wig conditioner in tub or pan of water to cover well. Do not rinse. Lay wig out on towel and pat out excess water. Pin on wig form and pick or comb out gently. If working on a long wig, start combing out the hair at the ends and work up the strand to the roots.