Picture a dragon. An ordinary dragon. What do you see? Flames burning down villages? Piles of hoarded gold? Dwelling in a darkened cave? But what if your dragon does not meet those requirements? Perhaps instead of shooting fire it spouts water that drowns entire towns or maybe it uses its ability to refill reservoirs? What if it can’t fly but struts through the countryside winking at villagers and befriending other magical creatures?
Take a typical ghost. She haunts the upstairs of the Victorian house on the top of the hill. She floats about terrorizing guests of the B & B. She dresses in a white gauzy dress, her ballerina-shoed feet never touching ground. What if your ghost lives in a modern high-rise condo complex in a major city? She has a nose-ring and wears punk-style clothing. Her attitude is obnoxious and rude. Her voice is a high-pitched squeal.
Your task is to take a mythical or magical being and make it your own. Choose a creature that you are somewhat familiar with, or spend a little time researching something from another culture that sounds interesting. Think of ways to make it your own. Choose a nontraditional setting. Change the characteristics as in the above samples. Alter the personality, food preferences, behaviors.
Write the story. Establish setting first, then drop in your character. Make things happen that will startle your readers. You want readers to smile, to nod, to enjoy the story.
Have fun with this.