People always wonder about proper Pizza Sauce, ultimately ending up applying Tomato Ketchup on Pizza Base.
I usually make the sauce as below (Taken From Here, with modification)
1) Put the tomatoes in hot water. After 10 minutes, remove the skin and Blend into a pulp.
2) Heat the oil and fry the onion and Garlic for at least 5 minutes.
3) Add 1/2 teacup of water and cook for 3 to 4 minutes.
4) Add the tomato pulp, chili powder, oregano, sugar and salt.
5) Boil on a slow flame for at least 10 minutes.
6) Use as required.