Via The Engine, learn how to write comics the Kurt Busiek way, as his 1988 writers guidelines for Marvel anthology Ad Astra are made public:
This memo is designed to give you the basics of how to use the comic book format. Some of this may seem extremely obvious, but I’d rather say something you already know than forget to say something important. On the other hand, some of this may seem obscure and confusing, and you may wonder how you’re expected to remember all of this stuff while writing a script The fact is, you’re not expected to remember it all; don’t worry about it. This will just get it all down in one place, so you have a handy (and hopefully concise) reference to check when you need it.
You’re also not expected to read this, sit down and write a finished script. If you have any questions, give me a call. If you’re not sure how best to handle a particular scene, how to make a plot more visually oriented or how to handle anything you have questions on, just give me a call and we’ll figure it out.