Before writing the argument, we must know some statistics that could help us with the basic structure of the argument.
Generally, novels are comprised of three sections (or three acts): the Beginning (exposition), that covers 25% of the overall book, the Middle (development) that represents 50%, and the Ending (resolution) which takes up the remaining 25%. If we bear in mind that a novel is on average comprised of 80000 words, the proportions are: Beginning 20000/Middle 40000/ End 20000 words.
The Beginning comprises the introduction to the story and that of the characters; it sets the status quo and creates a logical frame to introduce the first turning point in the plot, where you’ll present the conflict that our characters must solve. In a conventional novel, some 80 to 120 scenes or other important events take place. If we take the first number and calculate it to the initial percentages, around 20 scenes will take place during the beginning.
The Beginning reaches a turning point when the protagonist decides to act.
The Middle is where the story develops, the action itself, it will comprise 40 scenes, and around 40000 words. You will see the subplots (stories that involve secondary characters and complement or function as counterpoints to the main story).
The End is where the story defines itself and we see the consequences of the main character’s actions. This will have 20 scenes (20000 words).
Obviously, this is a very simple and shallow structure that might not adjust to the novel you plan to write, but it is truly useful in plotting the argument of the novel. Numbers will change, and it is likely that you’ll find yourself on the margins of these averages.