Heat the oil in a 3-quart (or larger) saucepan on medium-high heat. You'll want to use an oil with a high smoke point, like peanut, canola or coconut. If using coconut oil, allow all of the solid oil to melt before adding kernels.[1]
Make sure your pan or pot has a lid that goes with it.
The best popping temperature is between 400 and 460 degrees Fahrenheit. Oil burns at 500 degrees. If your oil starts to smoke, it's too hot.[2]
You can also add salt to the oil to help season the popcorn from within, instead of adding it on top after the popcorn is fully popped.