THE ROUGH DRAFT
Write whatever comes--you're going to revise it later anyway. Try to hook the reader on the first page, even the first paragraph & first sentence, if you can. You want the reader to keep turning pages, and that goes for an editor or an agent, as well as your targeted audience. There may be a terrific scene on page 47, but your reader won't see it if he isn't interested enough to turn those pages. Make your main character sympathetic, then make your reader care enough to continue reading to see how he solves his problem.
It is important to write your story as fast as you can while it's still fresh in your mind. You can do nothing with an idea until it's out of your head and staring at you from the paper or computer monitor. Hopefully, your story can and will be shaped into a coherant piece in later drafts. But if it can't, you've lost nothing with a first draft, and may even have learned something more about writing.