how to prepare my car for paint

hello, i'm new to this site and i have a question. I just bought an 89 caprice that is maroon and the paint is extremely oxidiozed so it doesnt look like much, so i decided to tackle the job of painting it a different color. Which leads me to my biggest question. How do i prepare the body for paint? I've heard that all i would need to do is sand it just a little and spray on a primer, but i've also read something about sandblasting, or buffing? i really have no idea so if anybody could give me some advice that would be great!