How does one write for a comic? Is it like script writing, or what? I'm very curious about this, especially because of the creative potential of the medium.
One of the Sandman graphic novels (I forget which), Neil Gaiman has an appendix where he says he gets asked that a lot, and gives at least part of the actual script he sent for one of the comic issues that was compiled into the novel, with some commentary (including how some things changed a bit in response to the artist).
Do you mean a comic book? A daily comic like those in newspapers? Or a webcomic? A graphic novel? BTW, writing for a daily comic is called gag writing.
What I have seen done (have read how Tiffany Ross does it for the 'Alien Dice' and 'Cyantian' graphic novels) is a very simple description of the scene and the dialogue. Each page is no more than 50 to 100 words. I guess really it's just memory prompts for the artist. I'd love to write a graphic novel but finding an artist that is interested and has the time is difficult. After all, anyone can write but very few can draw so artists always have their own projects going on.
Check out Understanding Comics by Scott McCloud. It's about both the art and the writing of comics and a great place to start if you want to learn about how to write a graphic novel.
It depends on the writer and the artist, but usually, for each panel there's a brief description and dialogue written out like in a film script. Sometimes the writer makes a sketch to show what he/she means. The writer usually leaves the panel layout to the artist. Stan Lee and Jack Kirby had a special method, where they'd outline the storyline together, Kirby would draw it, and Lee would go back and fill in the dialogue. I guess it works well if you have a very close working relationship. When Eddie Campbell drew Alan Moore's script for From Hell, Campbell used to ask his wife to underline the parts he needed to draw, because Moore was so wordy. I agree that Understanding Comics is a great book. I think it's more for the person who wants to analyse comic books like you analyse literature, than for the budding comics writer, but there are still many useful bits you can pick up.