It is best to buy the largest, most rectangular one that will fit in your oven. The round ones, though they conjure up visions of a perfectly shaped pizza, are less multipurpose, and can allow a lot of dripping. The rectangular ones are more flexible in terms of what you can make and what they will handle, not only in terms of pizza size, but also in terms of other baked things, plus they will be more likely to catch drippage.
You assemble your pizza on a baker’s peel or sheet or tray with no edges, first putting corn meal or parchment paper on the peel. When your pizza is all put together, you then slide it from the peel directly onto the heated Pizza Stone in the oven, with no pizza pan involved.
Clean a new Pizza Stone first with a baking soda solution, rinsing well (don’t use soap, it can be absorbed in.)
When putting a Pizza Stone on an oven shelf, leave a two inch (10 cm) space all round on the shelf, to allow air to rise and circulate. It will likely smoke the first time you use it.
Put the Pizza Stone in the oven when you start heating the oven. A sprinkle of water on the stone should evaporate immediately if the stone is hot enough to cook on.
A stone can stay hot long after the oven is off; always use oven mitts. Don’t remove a Pizza Stone from the oven until it is totally cool; some say that even the shock of sudden cooler air can crack it. Though, some may have flaws in them that will cause them to crack when cooling, no matter how careful you are.
To clean, allow the stone to cool, then remove, scrape off any food or drippings, then rinse with warm water. You can scrub with baking soda if you wish, but never soap, soap will go into the stone.
Eventually, over time, oils will go into the stone and make it non-stick, shiny and dark.