That’s the cliche. That's probably the most misleading advice any writer can get. It builds walls in the writer's mind, imposing artificial limitations that come from uncertainty. But I've come up with a variation which I think improves on that: write more than what you know. In other words, don’t be limited by using only what you already know.
Learn more and use it in your ﬁction.
My Veronica Slate mystery novels were all about a radio talk show host, something l know a lot about because I was employed in radio from 1964 to 1998. I was a talk show host before that became a questionable pursuit. However, Veronica got involved in things like a child pornography video ring, cocaine smuggling, and a theme park called Circusland, three things I knew very little about. Consequently, I learned what I didn't know in order to pair it with what I did know to create three entertaining books. If I had limited my books to only what I already knew, they could have been deadly dull.
Granted, there are some autobiographical elements in my books, but no single Veronica Slate book is limited to my life story. I've taken pieces of my life and distributed them to many of the characters in my books.
It’s better to use what has happened to you as back stories for various characters, not just the protagonist.
Don’t waste your whole life on just one character.
If you’re anything like me, you get angry when you hear that some idiot is killing gays or murdering abortion doctors in the name of God, or worshiping a madman. As novelists, we can do something about this:
We can create a story that begins with the thing that angers us and we can make it turn out the way we want it to turn out.
Fiction is a wonderful way to share your ideas with the public. Don’t preach. Simply create a ﬁctional world the way you want it to be. That’s the magic of ﬁction: You have the opportunity to change the way things happened in your life. You can take pieces of your real life, bend and shape them, and use them for ﬁction. You can get that job you didn't get, right perceived wrongs, or kill that nasty boss without getting hurt or arrested.
(No kidding. The ﬁrst character to die in Extreme Close-Up was named after a radio program director who used to give me a really hard time.)
I created the father I wished I'd had and gave him to Veronica. Fiction gives us the chance to change the World.
----- (From NOVEL SECRETS available in paperback and Kindle form.)