Use a mild soap, not detergent, (ie woolite, etc) in a bucket of lukewarm water.

Gently massage fabric, let the fabric soak for a few minutes.

Rinse.

Rinse again in a small amount of fabric softener. I use a teaspoon of baking soda in lukewarm water.

Hang to dry or put item in a washing machine on spin only cycle. Then iron, for a perfect finish. Or dryclean if you prefer.