Any good work of fiction has a basic set of components. Without these various elements, your book will be unsatisfying, or worse, unreadable. Many new authors make the mistake of copying or 'aping' an existing writer's style, or a popular genre - this can result in formulaic or cliched stories that probably won't be easy to sell to agents and publishers. The one thing to remember above all else is that any story, when reduced to it's most simple and basic level, can be described as 'There is a problem. The problem gets solved.' Of course, you need other components apart from a problem and a solution. You need characters, participants who can both create and solve the problem. These characters also serve another role - they allow the reader to 'identify', and make the story come to life in a way that would otherwise be impossible.
Many good stories rely on the '3 act' structure. Other structures are possible, of course - as an example, the plot generation software over at www.GetPlotted.com allows you to extend your novel in any direction your like. The 3 act story has a beginning, a middle and an end. Each act serves a different purpose, but all are equally important. Let's examine the opening act. This is a place for you to set the scene - introduce some of the main characters, for example. You can also 'foreshadow' here - that is, give the readers clues to things that will probably be happening later in the story. A story about a vigilante superhero, for example, might open with the young and terrified junior version of the character witnessing his/her parents being gunned down pointlessly in the city. This 'foreshadows' the development of the child into the vigilante later in the story.
It is also possible to set up conflict potentials at this point. By this we mean that a good character always has flaws. For example, if your hero is an Olympic champion swimmer, it might be useful to create a stress in the character by showing him almost drowning as a child. The hero has overcome a daunting flaw in order to reach a goal. Throughout the rest of the story, the character can always be stressed again to heighten tension, as the reader will never be quite sure if the flaw has actually been overcome, or simply suppressed. Character responses to temptation are good ways of demonstrating stress too. Having fallen once, the reader can never be sure the character won't fall again. You can short circuit the character generation process by using the character screens at www.GetPlotted.com - these have literally billions of random characters that you can use or tweak until they are perfect for your purposes.
In the opening act you should also show the reader who your protagonist and antagonist are. Most good stories have a 'hero' and a 'villain'. You want the reader to identify strongly with the hero - a good page turner novel will force the reader to invest emotionally in the hero from day 1. Note that heroes don't have to be perfect - the contract killer in 'Gross Point Blank', for example, is immensely likable because although he is a ruthless killing machine, he is also emotionally vulnerable and confused about his life. He's also nice to his mum - i.e. he has characteristics we can empathize with.
You should also set up the basic conflict that will run throughout the story - what is actually at stake here? In the Lord of the Rings, for example, after the pleasantries of a birthday party, it becomes apparent that nothing less than the fate of the entire world is at stake. And while we are on it, which world? Middle Earth? Modern day New York? Ancient Rome? The far flung future? Explain, because the seriousness of any conflict is very dependent on the setting. Your synopsis will need this scene setting - any editor or agent will need to be able to understand instantly what's at stake, without ploughing through 10 pages of story. The 'preview' section at www.GetPlotted.com generates a first pass story synopsis for you, and this can certainly reduce the time needed to do a good job.
And of course, you can set the overall tone for the novel, and foreshadow the ending. A Terry Pratchett novel is a comedy from the first paragraph. A Stephen King novel screams horror / unpleasantness / darkness from page 1. If your hero marries the heroine at the end of your story, you might shadow this by showing them as childhood sweethearts in the opening act. You get the idea - build layers into your storytelling (but don't become TOO complicated!). That way, the reader will feel like they are getting a full three-course meal in a fancy restaurant, rather than a Big Mac and fries. At www.GetPlotted.com stories are generally assigned a genre, and there are many of them, from romance to crime, to sci-fi or horror. By deciding on your genre first, you won't confuse the reader later.