
A novel is loosely a long fiction prose involving character and action and telling a story. The novel is longer (at least 50,000 words) and more complex than either the short story or the novella.
Novel Ingredients
In any case, any narrative more than a few pages long is doomed to failure if it does not set up and satisfy plot expectations. Plotting, then--however childish and elementary it may seem in comparison with the work of surgeons, philosophers, or nuclear physicists--must be the first and foremost concern of the writer. He cannot work out his sequence of events without at least some notion of who the characters are to be or where the action is to take place, and in practice he will never design a plot without some notion of what its elements imply. To say that plot must be the writer's first concern is not to say that it is necessarily the first thing that dawns on him, setting off his project. ... But whatever the origin of the story idea, the writer has no story until he has figured out a plot that will efficiently and elegantly express it. Though character is the emotional core of great fiction, and though action with no meaning beyond its own brute existence can have no lasting appeal, plot is--or must sooner or later become--the focus of every good writer's plan. - The Art of Fiction by John Gardner
Identify at least two plot twists... In a suspense novel, you need many plot points and at least two or three plot twists. The plot points and twists are the skeleton of your story. Character development, scene development, secondary relationshipts, etc. become the meat on the these bones.
... analyze your ending. Does it flow from steadily building tension, and is it exciting? The beginning and ending scenes are two of the most important scenes in a novel.
Do (the plot points) move the story forward, or are they merely repeating a pattern ... Each major plot point, aka fresh complication, needs to reveal something new. It can be either new action/evidence to advance a suspense novel, or deeper layers of a character to advance a relationship story. If you are not exposing something new every few chapters, your story will lose momentum and your reader will lose interest. - Plotting the Novel by best-selling novelist, Lisa Gardner