Buy the best used on take it home and wash good with soap and water Yes with soap and water. Rinse very good heat oven to highest temp 500 let oven heat up. Wipe with oil inside and out. Turn upside down or up on a piece of heavy duty foil or pan below rack allow cast iron to cook at high temp for 4 hours then let cool in oven for 4 hours. You will have a glazed cured ready to cook Cast
Iron Pot or Skillet that will last you a life time. Even if you buy a new one If you follow this procedure you will pass on to next generation. Some Old timers would build a hot fire with wood and place pot on coals and fill up with oil and let burn.
To clean after using if frying Bacon etc just wipe out if you decide to clean can use a light soapy water rinse good then put on stove burner on low heat for about 15 to 20 minutes. then wipe lightly with oil . the more you do this the more glaze you will have. I ave on from grandparents and is well over 100 years old. Looks like a well cured cast iron pot. I use for frying fish in or Black Pot Chicken or what ever. It sits on display in out kitchen. If you cure your self and do it right you will never be disappointed and can use and will enjoy.
There will be smoke at first for a while but pick a day open your windows, I put a little Rosemary and Thyme in mine when I do this it has a pleasant smell