Grant Morrison on his lengthy plan-then-distill method of writing Seven Soldiers and other comics:
I plan my stories very, very carefully, years ahead of completion but I l do like to let chaos and dirt into the proceedings, scuzz it up a little, forget the original intent, let new characters rise up and take over, cut stuff out, put new stuff in, add some NOISE. I've always preferred the Buzzcocks to Pink Floyd, if you know what I mean. I've spent 28 years in the comics business perfecting my 'sound' and it's been immensely successful for me but I don't really see it as two halves of anything and I'm not much of a one for duality so it's a more, dare I say it, holistic process as I see it.
All my work starts as sketches in the notepad - I have to have pages of visuals and designs or I can't get started. I then write a 'demo' of the first issue to music, in a fairly improvised 'Beat' way, just to get the tone, direction and energy down. This sometimes spills into a rough draft of the second and third and even fourth issues as well. The bulk of the original concept work usually gets done in a white heat over a few days - or weeks in the case of Seven Soldiers.
Then I fill up pads with notes and drawings. Seven Soldiers consumed several notebooks - I have the entire history of the Sheeda worked out, and the exact timing and days of the week on which the story happens. I know the entire geography of the fictional DC Universe New York. I know how every series could be developed into a long-running franchise and so on.
I work out most of the details to the very end then go to work in earnest - fleshing out the stories and drawing the connections between books takes as long as the comic takes to be published usually. I edit constantly; even at the very last moment before the book goes to print, I'm tweaking dialogue. I often write two or three complete drafts of an issue then throw them away [...] It can be an exhausting process but fortunately I work fast and reworking it in this laborious way means I get the material I like best on the page). Usually, the first drafts tend to come in around 40 pages which I then meticulously mix and re-mix until only the 'beat' is left and I have 22 pages of complete story. Every character requires a different storytelling style or rhythm - the Superman stuff I do is very tight and formal and magisterial, Batman is loose, pulpy and fast, WildCATS is remixed 90s New Rave and so on.
Once I get started on actual issues, I always find that the story and characters themselves take over and I generally wind up exploring completely different directions that often lead to a more organic ending. It's important for me to surrender completely to whatever the story and the characters want to do. I want to be surprised by my stories, to feel that I'm discovering them in a participatory way, rather than just 'making it up'. I like it when the stories and characters start to push ME around.