Add salt, but not oil
You may have heard that you can avoid sticky pasta by adding oil to the pasta water. This can prevent sticking, but at a great price. Pasta that's cooked in oily water will become oily itself and, as a result, the sauce slides off, doesn't get absorbed, and you have flavorless pasta.
Adding oil may keep the pasta water from bubbling up and boiling over the rim, but this can also be achieved by making sure you use a large pot and also by reducing the heat a little (but still maintaining a boil). This is a much better solution than greasing your pasta and sacrificing flavor.
Salted water flavors the pasta. A generous amount of salt in the water seasons the pasta internally as it absorbs liquid and swells. The pasta dish may even require less salt overall. For a more complex, interesting flavor, I add 1 to 2 tablespoons sea salt to a large pot of rapidly boiling water. By the way, the claim that salted water cooks food faster (because of its higher boiling temperature) is exaggerated; you're not adding enough salt to raise the temperature more than about 1°F.