Wash the skillet with hot water and a small amount of mild soap if needed
Scrub off any rust or old residue with steel wool or a stiff brush
Rinse thoroughly and dry completely
Preheat the oven to 450°F to 500°F
Apply a very thin layer of cooking oil to the entire skillet, inside and out
Wipe off all excess oil until the surface looks nearly dry
Place the skillet upside down on the middle oven rack
Put foil or a baking sheet on the lower rack to catch drips
Bake for 1 hour
Turn off the oven and let the skillet cool inside
Repeat the oiling and baking process 2 to 4 times for a stronger seasoning
After each use, clean with hot water, dry immediately, and add a light coat of oil