The first wash matters most. Wash a new cotton or hand-dyed piece on its own, in cold water, with a mild detergent. Colour will run a little the first time; that is normal, and it is why it should not share a bucket with anything pale.
Turn everything inside out. This protects prints, sequins and thread work from rubbing against the drum or the bucket.
Never wring embroidered or silk pieces. Press the water out between your palms or roll the garment in a towel. Wringing is what breaks zari and pulls thread work loose.
Dry in the shade. Direct sun fades dyes faster than washing does, especially reds and indigos. Hang kurtis by the shoulders, not the hem.
Iron on the reverse, on a medium setting, and put a thin cotton cloth over any sequin or mirror work. Steam a silk saree rather than pressing it flat.
Store folded, not hung, if the piece is heavy — a hanger stretches the shoulders of a beaded kurti over months. Refold sareees along a different line once a year so the creases do not become permanent. Keep muslin or cotton between silk pieces, never plastic, which traps moisture.