Handwashing in cool to lukewarm water with gentle detergent and laying flat to dry is best. If you must wash with a machine, do so on the gentlest cycle with cool water and a low spin speed. Never put anything in the dryer--it will shrink everything and ruin the silk appliqués. Hanging to dry instead of laying them flat is also fine, but it could stretch out the pieces. Do not dry clean or bleach.
After swimming, always make sure to at least rinse the swimsuit out with cool water afterwards--even if you don't have time to actually wash it. It is good to get the pool chemicals and/or ocean water out of the suit as soon as you can. Handwashing in lukewarm water with gentle detergent is best, but if your machine has a handwash cycle setting, using that every once in a while won't totally destroy the suit. The more you wash by hand, though, the longer the suit will maintain its integrity. Never tumble dry the swimsuit--always airdry, laying flat is best but hanging is also fine. Make sure the suit is completely dry before storing to avoid the growth of mildew. Never dry clean, iron or bleach the suit. When wearing, avoid brushing against or touching rough surfaces with the garment, because this will eventually cause the fabric to snag and pill.