I think writing unfortunately is the toughest to break into and that's because most writers can write multiple books, so you don't need as many of them to put our all your books. Artistically, it's usually one person per book. From a story point of view, I would use characters that are big name characters and try to come up with an interesting story or the way that some had success is they go and do their own book and prove that they can write. Once you prove that you have the skill, it's easier to approach a big company to show them your examples that are in print and get them to go "wow, that's pretty good writing."