As amazing of a tool as Cast-iron is, its still viewed by many as hard to maintain of to even restore. I can assure you thats not the case, lets walk through restoring a cast-iron skillet. It’s much easier than you think.
Paper towel/ Lint free rag
Scrub all rusty portions of the cast iron skillet with steel wool. Rinse with soapy warm water, the goal here is to remove rust. Any seasoning lost is fine as the skillet will be re-seasoned.
Grab a lint free cloth and dry the skillet. I personally like to place the skillet into the oven for 2-3 minutes to make sure it is dried completely.
Using a cooking oil with a high smoke temperature, like avocado oil. Apply a very thin layer to the skillet, enough to coat the pan but not enough to wear there is excess build up.