Draw a map of your world or the key elements that play a role in the story. Weather and climate, moons, names of seasons, months, hemispheres what wild things grow and run in the world? insects? vermin? who are the people of your world? are there more than 1 is that a problems? advanced, not so? some aspects? how much like ours? how does it change peoples lives? dont forget any special rules that your plot turns on.