I'm assuming that as a woman of color, your hair is very dry (like mine is). I'm also assuming you're keeping your hair natural (i.e. no relaxers). Washing once a week is fine. If your hair is short (up to 2 inches in length) you can wash it every other day. It's good to water rinse your hair first: rinse the hair in tepid water for a couple of minutes before adding shampoo to loosen the gels and products that build up in hair.
Be sure to use the best type of shampoo and conditioner for your hair type (Pantene, for instance, has a line of hair products for women of color). Also, stay away from products whose ingredients include petrolatum and mineral oil - those clog up pores and are actually really bad for your scalp (unfortunately, many many hair products have petrolatum and mineral oil, so you're going to have to spend awhile reading labels before buying anything).
Diane Da Costa, "Textured Tresses: The Ultimate Guide to Maintaining and Styling Natural Hair" (www.amazon.com/gp/product/0743235509/re...