Determine the general size and shape of your sculpture. You may also want to draw out a pattern.
Bend the wire into the desired shape using pliers. You may need more than one piece, and you can wrap pieces around one another. The armature should be slightly smaller than the desired size of the finished sculpture.
Wrap the armature in newspaper if you're using natural clay, and in aluminum foil for polymer clay. Natural clay may expand during firing, which can crack the clay because the wire doesn't expand at the same rate. The newspaper provides a cushion during the baking process. With polymer clay, the aluminum adds bulk so that you use less clay; very thick polymer clay also doesn't bake well. Paperclays may require either method depending upon the type of paperclay.
Cover the armature with a layer of clay. You may want a small slab of clay as a base to secure the armature. Sculpt, and avoid cutting so deeply into the clay that the armature is exposed.
Fire or bake the clay, if necessary. Some clays are meant to air-dry.