Square One of advice for writers is "write what you know." It's easier to develop inner lives for characters if you focus on things that have happened to you.
Ruta Sepetys weighs in on the subject with her own book, called You: The Story. Sepetys is a successful author of several works of historical fiction, and has rummaged through her own life in search of characters and plot devices and more. Her book lays out a potential path for fiction writers to follow, and we set out upon that path in this interview.