Effective fiction is world building. Pre-writing helps almost any fiction or campaign. Knowing what your bad guys did ten years ago and what the Adventurer's Guild considers its greatest accomplishment help you build a world. Those design notes also help you build some fictional bridges; if you dislike an idea, you can scrap it. If you like an idea, you can tinker with it.
Let's look at some examples.
Designer notes and rich, well-built worlds are insanely fun for fans, which we touched on recently. I'm notoriously bad at keeping my design notes for long. On my computer right now though, I have what I call "the scrap heap." The scrap heap is a text document where useless ideas go to germinate. They don't belong anywhere else? It goes there. Quotes that don't fit the tone of a story go there. Once I have been using it for a few months without having to farm it, it is a rich pile.
Those ideas, or other stories, can also be a way to jump into a different medium. For example, I'm a very visual thinker at times, I sometimes think of stories more like a comic book than in text. So, I often have set pieces that I try to structure an event around. In the story about Dana Littleton, for example, I had the shootout in the dark room plotted out for months, looking for a story to fit it into. You can take a set piece, for example, people stranded on a roof, and then build a story around it. Which is actually the basis of the current page-of-fiction-a-day story I'm working on right now.
The idea for the Dana Littleton short story began a few years ago, when I saw this unique style of revolver. I eventually combined that with robotic horses and Western adventure to get what turned into a 100-some page story about a desert adventure, where a little girl has a very big gun. The specific plot points, though, came from the scrap heap. For example, Radigan existed in draft looking for a plot for awhile. He's smart, efficient and utterly ruthless, but lacks the charisma to steal the show. Rennard is an archetype that shows up in most of my fantasy, the scholar warrior.
While I was in college, I was running a D&D campaign. Two of the background characters were interesting enough, that their history together ("Met to hunt ghosts") spawned a short story that is still half-finished. Likewise, the note "Adopted father lied about birth vision" spawned another short story from the same campaign. Neither of those stories have scholar warriors, with their magicians being more traditional caster types, but both relied on plot devices pulled from the scrapheap. In order: "Exorcise family ghosts" and "Anti-hero sacrifices family to save town."
"Superpower that sucks" will undoubtedly spawn many a story, though so far, it has only nudged me toward one. I even went back to rewrite the original ending because an idea on the scrap heap made me realize the original ending (cops catch and arrest bad guy, question him to prove his guilt) was nowhere near as awesome as "Hero gets revenge, but it drives him crazy."
Your notes are a powerful tool; they tie into your fiction's history. Not only that, though, they give you springboards to do more with that history. Your pre-writing is a crutch that will serve you well. Unlike magic, do not cast it aside.
About using a different medium for your notes, I would love to see a comic book retelling of the Guild Wars campaigns with the text from the campaign mission books to help introduce new players. Anyway, if you like listening to me talk about writing, table top gaming, random nerd things, fiction or history (and the weird synthesis of those things) follow me on Twitter or find me on Google+ (see the sidebar!) Also, follow the blog, because in the future, I'll come back to "Effective fiction is world
building." For now, start building your own scrap heap and your own
pool of d20 ideas.