Authors write books. That's pretty obvious. What isn't so obvious is that we writers should also be reading books. Not just books in our genre, but books outside our area of expertise. Anything and everything we can get our hands on we should be reading.
Now don't get me wrong. I'm a picky reader. I tend to stick to my genres, even going so far as to stick mostly to fantasy since that's what I write. I have a hard time picking up anything else because I don't like taking risks. But I've started reading a friend's BDSM erotica series (and it's awesome...her first book is already out and I'm the beta reader for all of the rest of them). I've read a few non-fiction books lately too. I'm listening to an audio book I got through Audible that's science fiction from one of my favorite authors.
But I'm also trying to work my way through the Song of Ice and Fire series. I've reread a bunch of Tamora Pierce's books. I'm reading a bunch of free fantasy books I've downloaded from Amazon.
I've also gotten a couple of paranormal/urban fantasy books from a friend. I'm reading those. I'm rereading 1662 and 1663, which I suppose are science fantasy because what happens to them is explained using science but it's still fantasy to me.
I'm not saying that we should go out and buy every book on the shelf. I'm just saying if you're a writer, you need to broaden your horizons. I know I do. I need to be more open to other books and other genres. Every book you read is a learning experience. Fiction, non-fiction, poetry, or encyclopedia. Open your eyes and your mind and read.