The decision about what decorating techniques to be used in most case is depended on the stage of clay.
Plastic Stage means the clay is still soft to be pressed, pinched, stamped or cut out. This state a clay form can be modified either its shape or its surface.
Leather-hard stage means the clay is dried enough (but not completed dry or too wet) to be handled without deforming. Most decorations can be applied in this statue such as carving, painting and color slip. This state is also good for jointing attachments and components such as handle, spout and small sculpture.
Green stage means a pot is unfired pot is dry completed, which is still in clay form. The pot in this state is stronger than leather hard ware, but it is still fragile. Since it has never been fired, it can go back to clay form after soaking in water.
Bisque stage that a pot has been fired once in low temperature that is often in cone 010 (900c). In this state, all physical water is removed during firing; clay is quartz and cannot go back to clay form. Bisque ware is easier and stronger to be handled, as it is harder than green ware.