1. Improved pasta
Never add oil to pasta water, it will prevent your sauce from sticking to the pasta. And also never rinse it as it removes the starches, just quickly add it to your sauce to prevent clumping. Also you can reserve a little bit of the water from the pasta for your sauce to add some body and flavor to it.
2. Better grilled cheese
Spread both sides of the bread with mayonnaise instead of butter. Mayo is more stable than butter and gives you a longer time to cook, which allows the cheese to melt more before the bread gets a chance to burn.