Many novice fantasy authors rely too heavily on the fantastical elements of the story and neglect to develop the actual story itself first. Before you can write a compelling piece of fantasy fiction, though, you'll need all the elements of a strong and compelling plot. For this reason, it may be helpful to create at least a skeletal outline to help you track what happens and to whom in your story.  Every plot should have some element that sets the story in motion. This may be an external conflict or an internal one, but something needs to happen in order for the action to progress. Rising action (in which the story develop and tension builds), the climax of that action, and the subsequent falling action are all crucial elements of a strong plot. The denouement (or "unraveling"), in which all of the tension is completely resolved, is essential to move the story towards its logical ending. A good conflict is critical if you hope to write a strong plot for any type of fiction. Conflict motivates the characters, catalyzes the story, and creates tension that the reader will engage with.  A common strategy is to depict the antagonist's motivations in direct conflict with the protagonist's. This creates a tremendous amount of tension and allows the reader to further identify with the protagonist. Conflict can be between a person and himself/herself, between two people, or between a person and an abstract concept (society, God/gods/goddesses, etc.). Characters are arguably more important than the plot. Even if a reader doesn't find the plot particularly interesting, he or she may continue to read a story because of its compelling and/or relatable characters.  Characters should have a clear, well-defined motivation. This can be a need/desire, a goal, or simply a personality trait, but it should be clear what makes each character tick. Try to make your characters contradictory or otherwise complicated, as this can make them more realistic. Remember that no one in real life is always good or always evil, so fictional characters shouldn't be, either. Make your characters vulnerable somehow. Whether it's a physical vulnerability or an emotional one, some type of human suffering/vulnerability makes characters more relatable. Map out more characteristics and motivations for each main character than you'll actually explicitly include in your story. Just knowing what makes your characters happy/sad/frightened/etc. can influence how you write that character in subtle ways. Infusing your plot with vivid details and complex developments will help bring your story to life for readers. Try to incorporate as many sensory details as you can so that readers get a real sense of what your characters experience and what your fictional world is like. You'll obviously want to include the sights and sounds of your world, but don't neglect the smells, tastes, and tactile feelings of that world. Don't drag your story on for chapter after chapter once the tension is resolved, but don't rush to be finished either. Figure out where the story should logically end by considering what readers may want to know about your characters in the chapter or two that follow the resolution of tension.  Make sure your characters resolve their conflicts. Don't try to have acts of nature, a new character, or some divine element fix all the conflicts, or readers will be turned off very quickly. If your story is part of a larger saga, you'll have to balance the logical ending for this story and the hint of what's to come in the next story. If your story is a free-standing piece of fiction, think about what questions might linger after the tension wraps up. Consider what happens to the principal characters, as well as what might happen to the world you've created after the central conflict is resolved.

Summary:
Outline your plot. Develop the conflict. Create interesting and memorable characters. Expand and develop the plot. End the story at a logical point.