0) crank your oven up as much as possible, and let it preheat for at least 20 minutes.
1) dough is super important - a slow rise in the fridge > 1 1/2 hour rise > 1 hour rise > store-bought dough.
2) Tomatoes in a can are always better than fresh tomatoes because they have already been cooked (trust me).
3) use the best mozzarella you can find, preferably mozzarella di bufala (made from water buffalo milk)
4) for the dough, use King Arthur Flour and bottled water - it makes a noticeable difference.