You should choose an oil with a high smoke point. I've successfully used safflower oil and lard* and the batch pictured was made with coconut oil (and, hence, it looks solid before it heats up). I don't think I'll use coconut oil again - I think it has too high a moisture content, because it was splattering like crazy.
We buy popcorn kernels in bulk at our co-op.
-popcorn kernels (about 1/4-1/3 cup)
-a saucepan with a lid
-a large bowl
So, easy-peasy stovetop popcorn:
1. Pour some oil and 2 or 3 popcorn kernels in a saucepan. The amount of oil doesn't really matter - you just need enough to easily cover the bottom of the pan.
2. Put the lid on the pan and heat on medium-high until the couple of kernels pop. Then you know your oil is hot enough.
3. Pour in enough popcorn kernels to cover the bottom of the saucepan in a single layer (this will depend on the size of your saucepan). Cover and pick it up off the heat.
4. Count to 30 while you shake the kernels around a bit in the pan (keeping the pan flat). Bean counts to 30 with me, so it's kind of the most fun step for him. This step covers the kernels in the hot oil and gets them all about the same temperature so they'll pop at about the same time and leave very few duds!
5. Return the pan to the heat, but keep it moving so the kernels don't burn.
6. Wait with anticipation for the popcorn to start popping! Keep the kernels moving, and when the popping slows to 3 seconds between pops, your done.
NOTE: The pan may get so full that you need to open the lid and pour out some of the popped corn before you're done. That's fine. Just do it carefully and return the pan to the heat. I set the big bowl next to me on the stove so I can easily do this.
Obviously, we don't do salt as a topping, but I do melt and add unsalted butter. I've also seen suggestions of melting butter into the oil, but I once stupidly used butter instead of oil and ended up with caramelized-buttered popcorn.....so I'm nervous to try melting the butter into the oil. (Though the caramelized butter was pretty tasty...just not what I was going for!)
I've also used a little grated parmesan cheese to top my popcorn, cayenne pepper makes a good topping as well.
*If you're going to share your popcorn, I recommend mentioning if you cooked it with lard. I once sent some to work with The Beast to share at a meeting and nobody knew about the lard until I mentioned it at a get-together several days later. I think some folks were a little weirded out by the use of animal fat. I hope they weren't vegetarians...(I felt pretty bad about the whole thing!)