Two secrets -
1) a seasoned cast iron skillet that's hot
2) white and yellow cornmeal. I like White Lily best, but it's hard to find around here. So Martha White will do.
So preheat your oven to 450 degrees, have your skillet in the oven with a couple of spoons of butter. If you have bacon grease you can use this instead.
I don't have exact measurements, as I eyeball it.
So take about 2 cups of the cornmeal. I use half white and half yellow. Add some salt and baking powder and sugar. I use the cup of my palm and that's about a teaspoon of each. Kinda swirl all that together. I use a salad fork. Add in two eggs and about 2 cups of milk. Buttermilk is best, but if you don't have that use whole milk. Yes whole milk. Don't use that 1% crap. Add the milk slow, because sometimes I use 1 & 1/2 cups of milk, sometimes 2 cups. It's better to reserve some than have your mix too liquid. Again I use my salad fork and kind of whisk it all together. Don't overmix. It should be thickish but able to pour.
Pull out your skillet (remember it's hot), dump your batter in, place back in the oven and pray your dogs don't bark. Takes about 30 minutes, maybe less, depending on your oven. You want to do the cake test - stick a toothpick in the center to ensure it still isn't gluey. Let it cool a bit before slicing.
Once you have basic cornbread down, you can make sweet corn bread by adding a 1/2 cup of sugar. Or you can make cake cornbread by using yellow cornmeal and self-rising flour (another 50/50 mix).