No matter what kind of kiln you are loading, you do not want to load ware directly on the kiln's floor. Doing so can damage the floor, especially in glaze firings, and can seriously disrupt the proper heating of the kiln by restricting air flow. Check the kiln's floor for cracks, debris, glaze drips, or other problems. If the floor is solid, make sure that it has a good coating of kiln wash. Do not kiln wash floors with electrical elements embedded in them. If the floor has a vent system port or burner port, make certain no kiln wash gets into those areas.
Begin the stack by setting posts for a bottom layer of shelving. You can use one-inch posts if the kiln does not have heat coming from below it. If your kiln does have a floor element, ventilation port, or floor-burner, I suggest using two-inch posts.
Before loading the kiln, make certain that all shelves are clean and free of cracks. Especially for glaze and test firings, also make sure they have been well kiln washed. Read Kiln Shelf Basics for more about these essential pieces of kiln equipment.