Show, don’t tell; write what you know; etc, etc.
I haven’t read Ruta Sepetys’s fiction but she seems like she can tell a good story. That said, this wasn’t quite the right book for me. This is an intro to writing book, but I also found myself vehemently disagreeing with her at times. On the other hand, I like that Sepetys isn’t uppity or full of herself despite her status as a bestselling author; she genuinely seems to like talking about writing.