There are a lot of plotting strategies taught today - The Snowflake Method, The wagon wheel, The heroes journey. These all have merit as ways to help you develop your story. If one of them works for you fine, but for me I always return to the classics. Classical understanding of fiction divides a story into six parts. If you understand the function of each of these parts, then plotting your story (even if you are a pantser and not a plotter) becomes more natural.
At it's core a story is simply this a person is doing something, but a problem arises, in trying to solve that problem several complications arise, eventually all those complications resolve themselves to one final problem to be resolved, after which the person can relax changed by the adventure be no longer engaged in it.
The classical elements of this type of plot are: exposition, action, conflict, complications (or rising action), climax (or crisis) and resolution (or falling action.)
The exposition is where we get to know the characters and who they are. We find out something about the setting and the motivations of the characters. Long expositions have fallen out of favor in our time, but if you read someone like Dickens, you will see several chapters at the beginning devoted to simply setting the stage for the story.
Today, however, this needs to be kept short and character introduction and establishment of setting is typically accomplished during the action and conflict portions of the story. However, some background, particularly in novels, may still be established in early chapters. For instance, cozy mysteries may take a "slower" approach and spend more time getting to know the characters in the first 2-3 chapters than say an action-adventure novel. Knowing the character had a passion for pistachio ice cream, lived 30 years in the same house, and generally made enemies of all his neighbors may be vital clues to unravel the mystery.
This is where more modern novels begin. The main character engages in some sort of activity. Let's take a simple paranormal romance story (as if romance were ever simple even without the paranormal element). Jennifer, a 50-year-old college professor teaches a class on horror fiction derisively called "Ghosties and Ghoulies 101" by her colleagues. The action begins as she begins a new semester of the class with a discussion of the horror classic Dracula. One suave gentleman about her age engages in the conversation in an intelligent and provocative way.
Jennifer's goal is simple. She just wants to teach another semester of her favorite night class. She is engaged in doing just that one more time.
If Jennifer just teaches another class successfully with nothing out of the ordinary happening, we really don't have a story. Something has to happen to change the course of the intended path the main character has set out for herself at the start of the story. Something has to interrupt her plans.
In this case, that interruption is Jonathan Langston, a suave 50 something, student with piercing eyes, graying beard and salt and pepper hair. Jennifer feels her heart race whenever she glances in his direction. She finds it difficult to avoid directing her lectures to him alone as if they are the only two in the room. She hasn't felt these feelings in years, so when he asks her out for a snack after class, she breaks her own non-fraternization policy and begins a relationship with this exciting, but mysterious man.
Some people misunderstand conflict. They think it has to be something dramatic like a dead body falling out of the ceiling or a shot ringing out in the night. Conflict is simply something that gets in the way of the main character's goal. In this case, her goal is to just teach another class without any change. Meeting and deciding to date Jonathan Langston changes those plans and sets off a series of complications.
Complications (or Rising Action)
The conflict spawns a series of secondary conflicts called complications. Take the book Huckleberry Finn by Mark Twain. The conflict occurs when Huck decides to help the Slave Jim run away to the north. Everything that happens after that in the book is a result of that decision.
Each complication in the story makes it harder for the character to resolve the initial conflict and bring the story to a satisfying conclusion. Let's go back to our paranormal romance. Jennifer finds that she is lacks energy during the day following her night class or a date with Jonathan. Jonathan's study group has had several students call in sick and drop out because of illness. Jonathan's fiction project spins an eerily realistic tale of two species co-existing on earth with one living off the psychic energy of the other providing the foundation for the vampire myths. She continues to get sicker. Jonathan becomes more distant and wants to break off the relationship, but both find themselves drawn back together.
Climax (or Crisis)
At some point all the complications culminate in a final conflict, the outcome of which will determine the future of the characters. This is like reaching the peak of a mountain you have been climbing throughout the story. This is where the hero battles the villain one on one, the detective reveals the murderer, the asteroid threatening earth is fitted with the rockets to divert it and the rockets fire, the final vote is taken at the board meeting to determine if you retain control of the family business.
Returning to our paranormal romance. It is obvious by this time that Jonathan is more than he appears to be. She is about to confront him at dinner when she collapses entirely. She is rushed to the hospital. She is found to be dangerously anemic. Jonathan visits her in the hospital and concludes the telling of his "story" to her about the vampire in love with the mortal who must leave her to save her. He kisses her and says good bye.
Resolution (or falling action)
After the climax, the world changes in some way. The mystery is solved. The bad guy defeated. The lover won (or lost). The world saved. And the character changes as well. Jennifer can no longer teach night classes. The night which once was so soothing in it's quiet darkness now only holds sorrow for her and her memories of a mysterious student with a remarkable story.