Peanut oil and chopped garlic to season the pot. Olive oil can congeal and leave a bad flavor to food if the pot sets for a long period.

Once as year or so, depending on the frequency of use, I fill the pots/skillets with wood charcoal and let it burn out. This adds a bit of carbon to the cast iron and also cleans out some of the accumulation of crusty matter.

Use a charcoal chimney starter not any chemicals such as lighter fluid to start the fire.

While the pot is still warm, empty the ashes (good stuff for the compost heap if you have one), give the pot a quick scrub with mildly soapy water and an abrasive cloth, rinse well, heat the vessel and re-season.

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now