The beginning of a story is perhaps the most difficult; it must accomplish a few imperative goals. The characters must be established enough for the audience to connect with them strongly, but not so transparent that the protagonist(s) become uninteresting.
The plot must also be recognizable in the form of clear goals, a progression of events, or illustrated through clever foreshadowing. With the amount of literature available today, modern writers are under a lot of pressure and scrutiny. Without enticing the reader in the initial section, the work has little hope.
The middle of the story reveals an impetus that blocks the protagonist's success. The character is complicated by circumstance, emotional responses or physical impairment.
The end. A climax is one of the most difficult segments to construct. It is a crucial moment in the novel, at which time the expectations of the audience and intentions of the author at once become clear, revealing a narrative thread that makes sense in retrospect, but did not force the story rigidly along.
There are a few notable exceptions, but the greatest writers are constantly working. Go to your local library or museum, where they might have old manuscripts or journals in which brilliant minds shaped their masterpieces. You will find incredibly complex diagrams, rewrites and notes, with many, many drafts preceding the final version, and often re-writes of previously released work.
Make a visual representation illustrating the characters' evolution and plot progression over the course of the work. It is very important to know where you're going; even if it changes, you have a complete idea that is being constantly worked toward, turned over in the mind and re-imagined.
Set up a schedule for yourself to write to, and fill your free time traveling or idly working to consider the work as a whole story. Try and see it from each character's perspective so you always have new ideas with which to work. What doesn't make it into the story is just as important as what does.
Check out the Writer's Reference Page online or borrow the book from your library. It may not be the most engaging task, but studying up on grammar is imperative for publishing work.
Keep reading. It will expand your creativity and provoke new thoughts. You will push yourself like your favorite authors, and if you keep your influences expanding, you won't settle into one stylistic pigeonhole.