It is perhaps easier to write contemporary stories for your world about your characters is already set. We know the sun rises in the east and sets in the west. What we don't know is what happens in a given day or time of our story. But when you discuss fantasy, you must take into account that idea of world building. You must describe, create, or at least attempt to bring the reader into that world which rest in your mind's eye.
Are you on the surface of a faraway planet? Does the soil shimmer and glow because of some odd element? Does it have two suns? A single moon with a ring? What is its name? Are there creatures like us or do they have features that need descriptions? This is what movie makers use a story board for. It can be an effective tool for writers as well. Picture your creature or hero/ heroine. Find pictures put them up on bulletin boards, make a scrapbook of your plot.
Yes, it sound tedious. But a well thought out plot often will save a writer from the dreaded writer's block. So get thee to thy story board and see if you can write that next best seller.
People to read:
If you are looking for examples of people to read to get the idea of a well developed plot please check out these authors.
Cheryl St. John
Examine your favorite authors. Critique their work and build your story