I start with a synopsis, trying to summarize the whole story in about one page of text. It helps with knowing the most important things that happen, and to make sure I know how it ends before I waste any time writing or drawing anything.
After that I write smaller summaries of all the story beats I want to include. It'll be something like:
- Character A and Character B have a big fight
- Character B kidnapping
- Character A rescues Character B
- Character A and Character B become friends again
It usually gets more complex than that, with a lot of scenes that I end up reorganizing when I start having an idea of how all the scenes and story beats might affect one another. You can use Trello for this, or write the scenes on postits and organize like that, or just use your writing program.
Along with this I also start breaking it up into chapters if it's a multichapter work, so I get an idea of how long the story is going to be.
After THIS. I start writing the chapters with dialogue. I don't decide page and panel breaks until it's time to start thumbnailing the pages, be that after I've written one chapter, or several chapters, or the whole story. I find this easier than being too locked in from the start.
For balancing story, characters and worldbuilding, I'll usually work on everything in tandem, so if I get stuck in writing, it might be because a piece of world building or a character isn't developed enough yet, so I just focus on that for a bit and it usually helps with solving the issue! I swear, the times a character design fundamentally changed a story because it made me realize the character wasn't at all what I initially thought.... lolol
ALSO, the final product is a comic, so don't get too caught up with the writing itself being good! You can write really shit sentences describing what happens, it doesn't matter as long as you know what to draw when the time comes. No one is going to read the script lol, so it's fine if it's just the bare minimum of description in there, if that's what works for you.