Like most of the respondants here, I tend to trip over ideas wherever I am. They just seem to pop up and then float around my head for a bit. The good ones seem to take on a life of their own, and develop plots and characters.
When writing I do not use an outline as this seems to stifle me. This is true even in school work where it would seem that I should be able to make an outline in advance. I recently took a college level course where I was supposed to turn in three different5 outlines for a research paper I was working on. This assignment was literally impossible for me to complete, the only way I can do an outline is to write the paper first, and I did not have enough time to write three seperate papaers, so I simply told the instuctor that I would not do the assignmet. As you can imagine this did not go over well, it seems I was the first poerson ever to say that to her.
Writng, to me, is about the free flow of words onto paper, not trying to force them into a preconceived notion. Every course I have ever taken has stressed the importance of outling, but my mind does not work that way. I have driven coworkers and study group members crazy as they tried to keep up with me. I put things off and do not folow a schedule, yet I always meet the deadline.