I find I approach my outline in one of two ways depending on what I am writing. My earlier attempts at writing were inveriably based around games of D&D or Rolemaster that I had played. As for these games I would painstakingly create complex, interactive worlds in which the characters would interact, when it came to the writing, the world and characters were already created. As the story tended to follow their adventures, the plot too would have been well worked out.
In the past year I have tried my hand at a few Middle Earth short stories. Here, again, the world and the characters are well documented, although not by myself. In some of them, for instance Balin's Folly, Watcher in the Water and Fall of Osgiliath the story has followed historic guidelines in which the outcome has been determined by Tolkien. Here I must write my story within the confines of his boundries.
In two of my personal favourites, however, Grud and Rangers of the North, I have tried to create something a little more original, still based around Tolkien's world and events, but outside of his boundries. I had a lot more freedom with these two stories than the others, and should have really made a story plan. In both cases, however, the stories just developed from opening paragraphs that I had been toying with. Both stories flowed as I wrote, the plot developing as it came into being. Grud, I wrote from start to finish in this way.
Rangers, with its more complicated plot, and a request from someone that the twins should be incuded in one of my stories, meant that I eventually had to stop and have a think about where the whole thing was going. It eventually became the culmination of three plots that had been running around in my head for a while. Funny thing was about this latter story, the only plot I had in my head when I began writing was that it was going to be about a young Rohan lad who would save a young Eowen from Orcs and that Gandalf would be involved. By the end of that first paragraph, however, that entire plot had changed and something else emerged as I wrote.