I know there are different ways to season cast iron.
I coat lightly with vegetable oil or crisco, put into a 350 oven until the oil begins to smoke (usually about 10 to 15 minutes). I then turn off the oven and let it sit in the remaining heat until cool to the touch.
If nice and shiny you are all set and ready to go. I also season the outside as well as the inside and the handle as well.
Humphrey's DownEast Beast W/BBQ Guru