Allow sauce to cook as long as possible, at least 1-2 hours or longer. The longer it cooks, the better it will be.
Depending on the type of tomatoes you use, your sauce may be to thick or to watery. If to thick, add a little water. If to thin, simmer uncovered, until it thickens.
Always make more than you will use for the meal. You can easily freeze the left over sauce. Use extra for pizza, eggplant Parmigiana or as a basic ingredient for barbecue sauce.
If you have any meat, you can add it to the sauce for extra flavor. You can use chicken, veal, lamb, pork or meatballs.
Use fresh herbs and spices, if possible. They will make any sauce taste vigorous! If you use dried herbs, place in your hands and rub your hands together. Then, sprinkle into the sauce. This seems to unlock the flavor of the spices!
Go easy on the salt, canned tomatoes already have salt inside.
You can use fresh tomatoes for your sauce. The tomatoes should be very ripe. Blanche the tomatoes in some boiling water and remove the skin. Puree in a blender or food processor. Some people like to remove the seeds of the tomato by straining. I just use the whole tomato.
I usually don't use oregano in my sauce. (Sometimes, I do, though.)