For a sweeter, mellower sauce, cook chopped onions until softened in a combination of extra-virgin olive oil and butter for your base.
For a more pungent sauce, cook finely chopped garlic in extra-virgin olive oil until just golden. Don't let the garlic brown or the sauce will taste bitter.
Chop all ingredients into even, bite-size pieces or smaller. Pasta is devoured with a fork -- there's no need to add a knife to the mix.
Add sturdier ingredients, like zucchini or eggplant, early on to cook through before adding delicate ingredients, like tomatoes or fish, which will break down if cooked too long.
For egg pasta dishes, reduce the sauce less, as egg pastas will absorb some of the liquid.
MAKE THESE SAUCES
Source Rachael Ray