Make sure it's fully 'seasoned,' by oiling it well. People used to fry potato peelings in them to help season. After that, be sure to NEVER put it in a dishwasher - it will rust. Some people say never use soap, but I've washed mine with soapy water & it works fine if you dry it over a burner (put it on a hot burner until the water evaporates), then oil it after it's cooled down. Just use vegetable oil, nothing fancy.
I love my cast iron skillets - they're the best for cornbread!