How to Cook Pasta: Here are the rules for factory produced, dried pasta.
Choose the right pasta for the intended sauce.
LOTS OF WATER - I use a 7 quart pot fill it with 6 quarts of water to cook one pound of pasta. WHY? The more water per pasta ratio, the faster the water gets back to boiling and the faster the pasta will cook. The more water per pasta ratio, the more room the pasta has, and this avoids sticking.
Do NOT put oil in your pan. Just use an ample amount of water. The exception to this rule is homemade, filled pasta such as ravioli.
LOTS OF SALT - Once the water begins to boil, add the salt and not before. Wait a few seconds until the water is rapidly boiling and then add pasta.
COOK Al Dente - Only cook the pasta until it is soft, yet still has a chew. Do not overcook. Test the pasta starting at two minutes before suggested cook time.
RESERVE some pasta water. Before you empty the pot into a colander, reserve a cup of pasta water for your sauce
Do NOT rinse pasta with water. The starch on the pasta needs to stay put!
FINISH cooking the pasta in the sauce. Place enough sauce into a large frying pan or dutch oven and finish cooking the pasta. It will absorb some of the sauce and flavor. At this time, add in some of the pasta water. The starch in the water will help to thicken the sauce.