Cast iron is the defining cookware of the Cajun kitchen, and for good reason: it holds heat better than any other material, it is nearly indestructible, and when properly seasoned, it develops a natural non-stick surface that improves with every use. A Lodge skillet purchased today, properly cared for, will still be cooking in your grandchildren's kitchen.
Seasoning
Seasoning is the layer of polymerized fat baked into the surface of the iron. To season from scratch, wash the pan, dry it completely, apply a very thin coat of flaxseed oil or shortening all over, and bake it upside-down in a 500-degree oven for one hour. Repeat 3-4 times. Each baking cycle adds another thin layer of seasoning.
Cleaning
Clean cast iron while it is still warm. Rinse with hot water and scrub with a stiff brush or chain mail scrubber. A small amount of mild soap will not ruin the seasoning -- this is a myth. What does ruin seasoning is prolonged soaking in water. Dry the pan immediately and thoroughly after washing, then apply a very thin coat of oil before storing.
Repairing Rust
If your cast iron develops rust, scrub it with steel wool until the rust is completely gone, wash and dry it thoroughly, then re-season from scratch using the method above. Rust on cast iron is not the end of the pan -- it is just a setback that a few hours of re-seasoning can completely fix.