I believe that the best way to learn how to write is to read a lot of books and write as much as you can. Reading books like 'Writing for Dummies' will only help you learn how another writer writes instead of how you write. However, this is an extremely helpful article that I recommend entitled 8 Ways to Write Better Characters. In this article are a few pointers on how to create intriguing characters and their relationships, personality, etc. If you are an aspiring writer, I encourage you to read other articles such as this one that don't necessarily teach you how to write but can help you in your journey to become a good writer.