Just let your imagination run wild. Think about things you're passionate about or experiences you've had, and build a story around them.
A good way to think of a good story is to ask 'what if' questions. Like, what if time travel was possible? Or what if animals could talk? Then build from there and see where your ideas take you.
Well, you could start by observing the world around you. Notice the little details, the interactions between people, and the emotions they show. That can give you inspiration. Also, try combining different elements or tropes to create something unique.