SCRIPT
So you have your story, either written by yourself or someone else. This could be a very detailed script or just a summary. We prefer to jot down the main lines and leave the details for the next stages. You might prefer to go for the detailed script and start thinking about and writing down the dialogs. Many artists do so at this stage.
We take our story and have a good look at it. How much info does it contain? Is it a short story, a one-book-story or a to-be-continued one? If it's the last one the first thing we do is divide the story into volumes. After that we work per volume (be it short or long). There's no real need to concern ourselves with future volumes unless we feel like it or the times has come for it.
Second step is to decide how many pages you want your book to be. European books tend be between 44 and 54 pages, but for our current story we ourselves prefer a number of 36, we find this just works for us. You have to find out for yourself what suits you best. In this stage there's still a lot you can change without having wasted time on artwork that might not be used.
Third step is to take a piece of paper, divide it into little squares (an A4 paper fits 36 squares nicely), as many as you have pages, and number them. Each square being a page, we divide our story over them. In each square we write down what we think should happen on that page. Make sure that, unless it's deliberate, scenes begin at the first panel of a page and end at the last panel of that page or a few pages later. You don't want a conclusion or a cliff hanger in the middle of a page, you want a nice flowing rhythm.
At this stage you may find that you haven't got enough information to fill your pages. It may be that you need less pages, it may be that you need to write more data. Or you might find out that you need more pages than first thought off, in that case you can decide to split the story in more volumes or just create a thicker book. Either way, not one picture has been drawn yet so you have all the freedom to experiment until you have the format that works for you.
If you haven't already, when writing your script it's where you start thinking about the details. For us this is also the stage where we come up with the jokes. Believe it or not, most of our stories begin rather seriously. It's when we get together and start throwing ideas at each other the fun comes in. Even when you work on your own, it's a good idea to let some trusted people look at your scripts and layouts to see if they work. Whether you are creating a comedy, a drama or something with a lot of action, it's important you don't lose the logic. Of course you can deliberately do things that aren't possible, especially in a comedy of a fantasy, and there's always something called artistic liberty, but never underestimate the intelligence of your readers. We ourselves are nitpickers and we assume our readers are too, even if not all of them are.