I'd always recommend writing something you know about it. Or even if you don't 'explicitly' know it, channeling some personal experience into a story. Or at least give us something to feed off to make for a suggestion for you.
Say I have ballet knowledge, writing a story about a OCD ballet dancer with jealousy issues would come across as authentic to me but many would struggle to pull it across with new prior experience there. You may have a great emotional experience that may be channeled into a story, that would come across as unique from you. Say, you had experience with (this is all hypothetical) growing up with a sibling with a severe disability. You would be able to write a great first hand insight, about how it shaped your life, how it gave you feelings of alienation, how family dynamics might be distorted because even if you are the 'younger' sibling, you have the caretaker role and 'older' sibling feel.