More cast iron

My apologies, because I know there are scores of relevant posts somewhere.
But bear with me. I've got a cast iron skillet that is a few years old, but, for various reasons I haven't used it in about a year. Its mostly been stashed away in my kitchen. Opinions requested . Should I season it from scratch or just cook something greasy? I've never felt completely comfortable that I fully seasoned it in the first place.