The clay I use is white, red or black low-firing earthenware. I use smooth or chamotte clay. Chamotte clay contains fine to coarse crushed particles of fired clay to make it more resistant.
Modeling is more instinctive. When medium or large-sized pieces are modeled, they have to be hollowed out so that they won’t crack when fired. And don’t forget to make a little hole at the bottom so they won’t explode in the kiln!