What do you love to do? What makes your heart sing? What would you do if you had all the time and money in the world? The answer to these question is where your passion lies. Write about what you are passionate about and the world will be yours. Look at little deeper and see what you know the most about within your areas of interest. Where your knowledge meets your passion is what you should focus your writing on.
Make a list of everything you love. Make another list of everything you know about, have experienced, or have worked at. Where do these lists come together for you? Do you love animals and did you once work at a pet store? This could be your area to write about. Do you love dancing and have experience taking dance lessons? You get the idea. Experiment in this area and see what comes up for you.