This might be a silly question, but I'm a complete cast iron noob. I managed to find a skillet at Goodwill today for four bucks (hooray!); it's in perfectly fine condition, but it's got some crud on it (understandable considering the source). I know enough about cast iron to know that soap and water is a no-no, but does that only apply after you've seasoned it? If I hand wash it and then re-season it, will it be good to go? Or is there some sort of esoteric stardust-and-unicorn-hair treatment I should use instead of dish soap and water?