How to make popcorn that's actually good
To make good popcorn at home without buying an expensive movie theater style machine, you need a Whirley Pop. The basic/cheapest aluminum one with nylon gears is fine; I've been using mine for 10 years now without any problems (Amazon's Whirley Pop page tells me: "Last purchased Jan 23, 2014").
If you want it to taste like typical movie theater popcorn, you need Gold Medal Flavacol, which is a butter-flavored salt that most movie theaters use, and is the key ingredient for the distinctive taste. A 35-ounce carton of it for $9 will probably last you for years (I'm on my second carton in 10 years, and it's still nearly full).
I use:
• 1/2 cup of Orville Redenbacher's Original popcorn kernels
• 3 tablespoons of refined coconut oil (don't get unrefined; popcorn isn't supposed to taste/smell like coconuts)
• 1 rounded teaspoon of Flavacol
I preheat the oil with 3 popcorn kernels in it, and when they pop I add the rest of the popcorn kernels and Flavacol, close the lid, and stir until done, which should take about 3 minutes. You may need to use trial and error to find the heat setting on your particular stove that results in a popping time of ~3 minutes (you don't want it to take significantly more or less time than 3 minutes). Also, don't force the crank handle when it becomes hard to stir because it's full of popcorn (that's how those nylon gears get broken). Just stop stirring; it will be fine for the 10 or 15 seconds it takes to finish.
Then I immediately dump it into a paper grocery bag, pour 1/4 cup of melted butter over it, and shake it up for a minute.
You could eat it at this point, but contrary to how good it may sound, "freshly popped" popcorn isn't really a good thing, because it still has quite a bit of moisture from all the steam that was created when it was popping, and that can make it kind of tough and chewy.
When you buy popcorn from a vendor, they usually scoop it out of the bottom of the machine where it's been sitting over a warming element for some time. That warming element dries it out and makes it tender and crispy. To duplicate this critical aspect at home, I put the popcorn, paper bag and all, in the oven (preheated to 200°F) for at least 20 minutes (I don't know the upper time limit, but I know it's fine being in a 200-degree oven for an hour). It's worth the wait to me because no matter how good the flavor is, if it's tough and chewy it sucks.