Writers must be a little crazy.
A writer will plot out their story, writing outlines and summaries, so they know what they are trying to tell. When the time comes to actually sit down and put words on the page, something very odd happens.
Characters disrupt stories. Perhaps this is their place, and is what makes stories come to life. A good story might have an outline, but the characters have to be alive. Turning an unexpected corner, saying something you don't understand, or even just showing up out of no where. Characters are what drive the experience that a reader has with a story. People are disruptive, so too should be the characters we read and watch.
As a writer, I love the fact that I don't always know what is going to happen next. When I plot things too strictly, I start to lose interest in the story itself. So, generally I plan out the large strokes of the story. The place where the movements of the tale will hopefully go. I think about methods of expression, and in some cases how to filter the events through the voice of the narrator. Sometimes it is hard to do this without trying to plan things out to a fine point. You see flashes of moments you want to capture in your story, and you fall in love with those moments. While pretty, they still need life. If your book was a painting or a photo, it would be easier to let that one moment live. But without the baggage, desires, and ignorance of the characters involved in the moment, the moment itself loses all power.
Writing in the first person comes with its own unique set of challenges. The perspective of your story is locked, and you must do everything you can to maintain the narrator's viewpoint. Sometimes you, as the author, want desperately to let the reader know what is going on in someone else's head, but you have to limit this urge. There are other times when you want to throw the author's shadow over events that are about to happen, but you have to be careful there too, else your narrator just becomes a predictor of all things that could happen, and the story becomes boring.
First person is also amazing to me, because of the flaws in your narrator's perception. Often readers forget that characters telling the story are also just characters within the story. The things that they pass off as fact are not necessarily so. Our real world is filled to the brim with people who all have very different opinions over the tiniest of events. In order to make your characters flawed, like real people, they cannot know everything. Sometimes what they know should be wrong.
I find delight in flaw characters, but I also like deep characters. First person sometimes makes that second part hard. If the narrator doesn't pay much attention to others in the story at some point, it can make them seem flat. This is an issue that requires a very delicate balance, and often you will need to make an artistic choice on how to deal with that sort of interaction.
As someone once told me, "Conflict should bleed from every page..." This conflict does not have to be bloodshed or overt argument, it can sometimes just be doubt. Layered conflicts scatter wonderfully when your characters make a decision that you hadn't planned for. Each wheel that is a character in the story now has to make decisions about every conflict that they face.
Disruption is a wonderful thing.