"Basically I am doing it as a script but I am reading books about drama and playwriting and using that as my model rather than screenwriting because I think it's closer to what I want to do with my comic. Although honestly I think comics (longer ones, like graphic novels or whatever you want to call them) are closer to cinema than anything else. I mean a storyboard is basically a comic book.
Now I just have to write each scene so I can start drawing the chapters. I'm leaving the very end of the story a little open-ended and I plan on working on the first chapters as soon as I have the scripts done, because I know certain details, etc might change along the way and in that case I'll have to revise scripts and change dialogue, etc.
Dialogue is pretty difficult but I keep a voice recorder and get my husband to read scripts outloud with me or just create the dialogue -- then I type it out and edit it so it reads better. Actually, this is the hardest part of writing a comic.
PS- In short, I write scripts, then draw the comic. Although I get my character sheets/designs done before I do any of that (except for secondary and incidental characters, which I work on as I write the story) and sometimes I sketch out principal parts of scenes as I write."