Hand Wash

If your costume will withstand water, you can easily hand wash it. If the clothes has multiple colors, remember to add a little bit of vinegar to prevent dyeing. If you need extra whitening or stain boosting power, try a little bit of Borax. Fill a sink or basin with cold water. Add a small amount of gentle detergent (or shampoo). Turn the costume inside out, gently kneed the costume by hand for a minute or two. Rinse well with cold water to remove all of the detergent. Hang the clothes or lay it flat to air dry. Do not use a clothes dryer as this can damage your costume.

Spot Wash

Dilute detergent in water and gently dab areas that need cleaning with a wash cloth. When you are done go over the spots again with just a damp cloth to remove the soap residue.

Drying

Whether you are using a machine, hand washing or just spot washing, it is probably best to dry most cosplay costumes laying flat. If you have a drying rack, then you are a step ahead. If not, then lay it carefully on a bed of towels. Be sure to change the towels out and flip your costume over so that all sides get aired and a chance to dry.

NOTE: Always test your material before trying any cleaning method. A good hidden (or at least un-noticed) spot is the inside hem of your pant leg.

As a general rule, you should store your cosplay in a cool, dry closet or storage area and avoid excessive sunlight. It's best to carefully fold your costumes or hang them up depending on the type of material used. If possible, it's also best to keep costume props and accessories alongside the cosplay.