Here’s a creative process I do, that works for me. Your process may be completely different.
All my good ideas start as bad ideas
I get an idea, and I get excited. I brainstorm a lot of stuff. In this case, I’m putting together a game scenario, and I’m writing up setting, a history of the city, politics, cultural bits.
Next, I go back through that, and focus on the situation, first. If I only have a one shot, what’s the stuff I could reasonably explain to a player and have them remember, and understand the scenario?
Usually I find the scenario was messy- there was probably 3-4 things that could be the focus, but now I cut it to 1-2 things that are the things I really am excited about. Don’t worry, it doesn’t mean the scenario will play out as a one-trick pony – the focus makes it easier for me to adapt in play because I have a better grasp of what is cool about the scenario…
Funny enough, I have to go through this process- if I just started with a “simple” idea, it inevitably turns out to be too broad, vague, and bland – the complex idea gives me a lot of edges and angles to choose from, and cutting it down lets me pick the best, most compelling stuff. And, the process of having done that gives me a lot of background ideas that I can pull out during play and make it seem like it’s off-the-cuff when it’s partially discarded or reworked ideas.
A cleaner idea is a cleaner game
My group and I play lots of short campaigns or one-shots – we get to switch being the GM often enough, and we get to look at what each other is doing as GMs or players and compare notes about what is easy or hard for any of us. We learn from each other.
A lot of times, a common thing for all of us is the tendency to get derailed or unfocused – to spend too much energy as a GM on something that ultimately doesn’t contribute to the game. It makes it harder to adapt in play to what is really interesting and cool, and also confuses the players along the way.
An unfortunate thing I see happen a lot in rpgs is that many folks try to be “clever”.
Other media have the advantage that people can re-watch/reread something to figure out if something is complicated or unclear. Rpgs do not have that luxury, and, furthermore, because the fiction is created by the group, it becomes absolutely vital to clearly communicate what is necessary to know about the fiction – or you end up with situations like, “I grab the bag”, “But you’re in the other room!” “Wait, there’s two rooms?” “Yeah, you went through the door” “Oh I thought I was on this side of the door…”
When you can have mixups on simple things, being clever is often asking too much.
Good prep is a seed, bad prep is a husk
Good, clear prep that is focused works as a seed in play- it naturally creates more things.
An old piece of gamer baggage is to over-prepare material on the idea that “it’s better to have too much than it is to risk not having enough”. This mostly comes from D&D dungeon building or railroaded encounters- where anything that is available had to be prepped before hand, and usually took 2-5 times as long to make as it took to play through.
Problem is, that stuff is all 1-shot material (“We had the encounter. We’re never going to have that again…”) and you end up having to navigate through it during play, instead of having a flexible idea you can build off of.
Worse, if the material isn’t relevant or interesting, then it becomes something you have to work to discard, or, the players have to wade through to figure out what is important. (“Ok, so in the room description he just read 3 paragraphs about the tiling design. Is this a clue or is it just a place where Gygax decided to go off?”)
Bad prep is a husk you have to peel away to not let it clutter up the things that matter.
My recommendation is to brainstorm, then cut it down to elevator pitches and reframe any idea cleaner. You’ll get more from it, and better play.