The principle to make a sugo is the following: first, fry onion and/or garlic with olive oil, until brown (you can add also other vegetables like carrots and the like, but that is not necessary). Then add the tomatoes (and salt) and let the sugo cook, on low fire, for a long time, until the water evaporates and the sugo thickens. Towards the end add pepper and other spices if you like.
That's the principle. Then one can do all kinds of experiments and all all types of things. Things that have to brown and cook well should be added before the tomatoes (eg carrots, peppers, fresh mushrooms, and the like). Things that have to remain whole or don't need to get brown should be added after the tomatoes (eg dried porcini mushrooms, anchovies, olives). The doses given below are just an indication. In fact, you should change them to suit your taste. The important thing is not to be shy with olive oil. A lot is good.
An anti-splatter grid to cover the pan is extremely useful if you are not paying somebody to clean the kitchen the day after. When the sugo is boiling on the fire, it can send out oily drops to unimaginable lengths. One of the first places where these drop will land is of course your shirt. Aprons are a wonderful thing, but they're not enough. A change of shirt is the easiest thing. Minimizing such events is one of the reasons to cook the sauce on very low fire.
Another important notice: the sauce will be very, very hot, and when the water is evaporated, it will have more heat than boiling water. Tasting the sauce without precautions will burn your tongue right away. It is best to lift a small spoon, let it rest for a minute, then go. Even better, dip a small piece of bread in the sauce, then let cool.
Regarding the choice of pasta, there's really no rule. However, liquid or watery sauces go with spaghetti, thick and chunky ones go with other smaller shapes. The reason is that spaghetti absorb watery sauces very well but do not hold thick and chunky ones. Shapes like penne or fusilli hold chunks much better.
This quantity should serve 8-10 people (and more).
Actually, what I do is rather to prepare large quantities in the summer (I mean, 30 pounds or more...), when you can find tasty fresh, ripe tomatoes in farmers' marketx, and then can it for the winter. Since the sauce is extremely hot when done (more than 200 degrees), canning is easy.
Cut the onion, the green onion and the carrot in small pieces. (you can use a food processor. You can add the olives at this stage if you want). Wash and strain the capers, and cut them as well. Pour the oil in a pan or skillet, heat it, and pour the things you just cut, plus the garlic cloves. Let them fry until the onion is golden brown, always stirring to avoid burning. This should take approximately 10 to 20 minutes, depending on the temperature (much less if you have a very powerful fire). Note regarding garlic: if you use whole cloves, the flavor will be very mild, quite unlike the usual flavor of cooked garlic. If you prefer, you can cut the garlic in pieces, and then the flavor will be more intense. If you do so, use less garlic. Also, it is necessary to have at least one main thing (onion, garlic or shallots). The rest is optional (carrot, green onion, etc.)
When the onion is almost ready, add the liquor and let it evaporate, always stirring.
At this point, you can add the tomatoes (which you will have cut into pieces), the anchovies, the olives (if you haven't done before) and some salt (but may be not too much, you can adjust it towards the end).
If you use fresh tomatoes, I suggest you take the skin off. I have a machine that takes the skin off and cuts the tomatoes, or you can use a vegetable strainer. More simply, you can boil the tomatoes for a minute in hot water, and then the skin will come out easily. (Beware - the tomatoes will be hot).
Regarding the olives, I actually prefer to sautee them separately and add them at the end. To do so, cut the olives in small ring, fry with oil in a separate pan for a little, and then add them to the sauce at the end.
Let simmer on low fire. Cover with a grid, as explained above. Mix every 5 minutes or so to avoid sticking, although, if you use a non stick pan on low fire, you shouldn't need to do this too often. The sauce is ready when the water has evaporated and the sauce is relatively thick, approximately halving in volume (but you can have it more or less thick than this, it's up to you.) Towards the end, add the spices, black pepper, thyme, hot pepper, whatever you like. Don't be shy, a lot is good (except for hot pepper). Remember that you will pour it later on a big quantity of pasta so the spices will be subdued by all the carbs.
The cooking should take anywhere between 1 hour or two (or more), but it depends on the intensity of the fire and the quantity of sauce. If you are preparing only one portion in a frying pan over very hot fire, you may even be able to cook the sauce while boiling the pasta. When ready, you can use it immediately, or store it for up to one week in a refrigerator (the oil will help preserve the sauce, the more oil you use, the longer you can keep it).
You can also can it. To do so, simply pour boiling sauce into a glass jar, filling almost to the top, then immediately put the cap on, and then turn the jar upside down (to sterilize the cap as well). Note that this is not the secure way to can things. To do things properly, the jar should then be boiled for a long time. But I have never had problems by simply pouring boiling sauce in the jar. However, do so at your own risk.
For a tastier pasta, you should warm the plates in the oven before serving (otherwise the pasta will cool down too quickly). You can also mix the sauce and the pasta for thirty seconds or so in a pan over the fire, for better sauce absorption.