I never bothered with the butter etc, though maybe I should.
As the popping slows, I take the lid off entirely (there's enough popcorn at that point to keep new popping from splatter or jumping out), and add salt, and then rotate the bulk of the popped corn with a bump to one side, salt again, bump-rotate, etc, getting the salt on it evenly without letting it cool too much. I like popcorn that's just-popped hot.
Two other notes:
I only use peanut oil, because at fast popping temperatures, some oils smoke. The popcorn does not taste like peanuts, if you'd worry about that.
I use more oil than most commenters, such that the single layer of kernels (3/4 cup in my pot) are nearly submerged at the start. Cleanup is more involved than a wipe of the pot, but the popcorn is a lot tastier and I don't need any butter or parm.
The silicone bowls are by far the best. Big consistent, crisp pops. Minimal waste, you can even repop the unopposed kernels. But easy to burn if you are not careful.
Air poppers are by far the worst. The pop corn always came out like styrofoam. I’d bite into the popcorn and it would just flatten.
I don’t believe the comments about getting minimal un-popped kernels using a pot, by just swirling around a bit of oil. Sounds like baloney to me. Results are good but waste is relatively high in a flat bottomed pot.
The best vessel for stove top is a metal container with a curved bottom - wok, large metal bowl. Add popcorn and oil as normal. Heat for about a minute. Turn the heat off. Stir the kernels for 30s to a minute to let the heat even out. Turn the heat back on and cover. As they pop shake the container to help the kernels settle to the bottom. The same technique can be used in a normal pot, but the heat distribution is not as good.
It works, though!
I use an ordinary 3qt pot (Cuisinart MCP193-18N, if it matters; this is a tri-ply pot). Choose enough kernels to make a single layer on the bottom of the pot (that's about 1/2 cup for this one, if I'm remembering correctly... I'm usually on autopilot doing this though) and set aside. Add enough oil to the pot to basically half cover the single layer, or a bit more. Add five kernels to the pot and start the heat at medium-high to high. Add the rest of the kernels when 3/5 of the test kernels have popped. Cover with lid. You're done when the pot is full (and it will be!). Pour the popcorn into a separate bowl to season and serve.
Works every time, with very little waste kernels.
I took or adapted my stove top method from Alton Brown. And it works on every wok so far.
I guess you don't have to believe it, but I rarely get more than two or three unpopped kernels that way, personally.