Sort laundry by color before beginning to wash. Put light, pastel colors like yellow and pink in one group and dark colors like navy blue and brown in another -- keeping whites in a separate group. Or you can separate by color type. Put red family colors like pink and orange in one pile, blues in another and so on. Colors may appear to fade if they bleed from one piece to another, and washing like colors together reduces this effect.
Turn colored clothing inside out, which helps prevent fading.
Wash in the coldest water available to further prevent fading. Dark colors, in particular, should always be washed in cold water.
Tumble dry clothes on a low-heat cycle. If you line-dry your clothing, hang it in the shade instead of the sun. And take it inside as soon as it's dry, to avoid fading from the sun.