In ten simple steps, you too can plot like a Grim. 1. Get an idea
This can be a brief snippet of dialogue. Or an ending that just seems perfect. Sometimes it's just the concept of what I'd like to see a character go through. I write that down. Usually it doesn't see the cold light of day for at least a couple months, but when I've thought about it long enough and can't seem to get the idea out of my head, that's when I sit down and start plotting things out a bit.2. Work out the basic plot
Now that I've got the idea, I need to work out the basic details. But how do I do that? Well, I write it down. Then I think about the different angles to get to that idea. I write those down. If it's dialogue, who's talking? What do they feel? Who are they talking to? If it's a snippet of a scene, who's in the scene? Why are they there? What are they doing? What's going on outside of that scene?