What is the best way to restore a cast iron skillet?

http://www.hometalk.com/diy/clean/cast-iron-skillets/how-to-clean-rusty-cast-iron-pans-23562937

Bake it at a high temp with crisco in it. When it cools a bit take steel wool to it. Wipe it clean and repeat the hi temp part.

Get a big fire going in the fireplace (or bonfire outside) and through the pan in. Let it stay at least 30 minutes, get it out and let it cool naturally (no cold water). Then rub it all over with canola oil or unsalted butter and put in in the oven at 250 for about 2 hours. That will season it, and you're good to go! I burn off my skillets about every other year or so.

some say not to wash the skillet....yuck. i wash/ scrub rinse and dry over a burner . when dry i add olive oil as it doesn't turn rancid as quick as other oils.

You need to "season" your cast iron skillet. Simple process, here you go!

http://www.lodgemfg.com/use-and-care/what-is-seasoning

Use salt and a soft rag or sponge to clean it after every use. Never use steel Wool!

put a small amount of salt, enough to clean with, rub around in circles, rinse with warm water.

Wash in hot water and dish soap--dry completely. Grease well w/shortening (something solid at room temp )like Crisco or lard. Bake in oven for 2 hrs at 250*. Lodge cast Iron products may have a similar suggestion. There after wipe clean and lightly grease after each use.

If it is caked up with old crusty grease, put it in a bonfire until it's burned clean. Scrub it. Then start the seasoning process, greasing it and put in the oven.