Everybody on Earth or in orbit has a unique life experience. No two people are precisely the same. We get told this a lot, but it's a pretty useful thing to consider when you're writing fiction. The things you've experienced, and the topics you've pursued or studied, contribute to a unique persona, and that translates into a unique style of writing. This could, I suppose, be considered an aspect of "write what you know." Or it could simply be a statement that you're going to write what you know whether you intend to or not.
There are a lot of story ideas out there. One might even say there are infinite stories out there. Which ones are yours are going to depend a lot on your specialty. How you execute the classic ones is also going to depend on your specialty.
I came into fiction writing with a specialty in language, linguistics, and culture. Even when I'm not specifically focusing a story on a language or culture-related premise, that's going to show through. I have the knowledge in these areas, so I'm not going to let myself cut corners. I'm not going to do something that's patently ridiculous - and my definition of patently ridiculous is going to be a lot stricter because I've spent a pretty ridiculous amount of time becoming acquainted with these topics!
You might think that the ideas that are "out there" in science fiction and fantasy are finite. I've heard people argue that. The ways of approaching them, however, are not. The reason that people in English classes and writing classes study the historical context of the writing of a piece is that the societal issues of the time are often reflected in the stories being told. Well, so are the life conditions of the author. Your life conditions change those ideas that are "out there." Your special viewpoint makes them your own.
I have a terrific writer friend who has a nontraditional family, and who has a background in theater. That means that she has special expertise in portraying certain types of nontraditional families and the individuals who might be a part of them; it also means she has a great sense of dialogue and movement in her character interactions. Another friend of mine has tons of teen interactions through gaming; that gives her teen characters a lot of realism and intensity. More than one of my friends has experienced intense suffering, and they are able to portray remarkable emotional range in their writing.
I find that people often aren't aware of the ways that their life experiences influence them. They might be very good at something due to personal experience and not even realize it. When I first came into sf/f writing I thought of my studies as a delay in getting to what I really wanted to do; quickly, though, I realized that they were the reason I could do this successfully, and stand out. It's really valuable to consider what might be your specialty. Take a step back from your life experiences and think about the ones that have most profoundly influenced your mindset. Then look at what you've written and see if you can find the footprints of those experiences. If you never have before, consider taking something from that core expertise of yours and putting it at the center of a story. Your specialty will become a solid foundation for whatever you plan to build there.
It's something to think about.