One part cat shampoo to five parts water should be used to wash a cat, according to the ASPCA. Bathing a cat is typically only necessary if it is extremely dirty or smelly because cats are capable of grooming themselves well using their tongue and teeth.
Choose a time when the cat is in a mellow mood to give it a bath. It may be necessary to play with the cat in order to tire it out before giving it a bath. Make sure to clip the cat's claws before placing it in the water to prevent scratches, and brush through its fur well to remove excess dirt, fur and tangles.