1. Be a reader. The first requirement to be a writer is to be a reader. If you enjoy reading then your audience will enjoy your writing.
2. Write what you read. If you prefer romance or westerns or sci-fi or mysteries then write that kind of book, because then you will have fun writing your story. If you read self-help books then start there.
3. Write what you know. Why spend thousands of hours researching a subject where you have no experience? Glean from your life experience and harvest your memories.
4. Study your craft. If you want to perform good work then you must do your homework. Observe the techniques of great writers and read books on how to construct a grand argument story. You know people who brag about their artistic or musical skills but if they have never taken lessons then they will always be an amateur. Be a professional. Study the craft of writing.