When John decides to explore a form he's usually thought about the shapes before sketching them out in his notebook. Things to consider include the ultimate purpose and the user experience, which includes the glaze, the surface texture, the size. When he's ready, he'll play with clay with no goal in mind, allowing his hands and mind work together.
He tests new glazes at each firing, which also plays a part in the development of a new idea. There is always several glaze tests in each firing.