Creating A Horse For Geronimo - The First Clay

I'm working on a 1/4 life size figure of Geronimo on horseback. I'm using an 18 inch human armature for this figure that will sit on top of another armature of a horse by the same company.
If you wish to order armatures go to http://www.truformarmatures.com
Here's where you can buy my kind of clay.. I use the medium grade
http://www.sculptclayandtools.com/Products_clay/2-AB225.htm