I've picked up old ones that needed TLC and have used the fire method before. I've built the fire and then raked out some coals, put the pan on the coals and after 20 min or so put coals into the skillet and tossed wood on top. Pull it out of the ashes the next day, rinse, dry and scrub with salt. Rinse and dry it again, then season it kind of like slawburger says to do. I smear a thin coat of veg oil on it, put it in a cold oven upside down and start the oven. When it hits 350, kill the heat and let it cool in the oven.