One of the oldest bits of writing advice is: Write what you know. I remember being told this as a young writer and thinking 'But I’m too young to know anything.' Indeed, taken at its most literal there would be many fewer plays by Shakespeare since he'd certainly never been to Italy where many of his plays are set; there would be no books by ...
One of the most common pieces of writing advice is "write what you know," but how many of us truly know what it's like, say, to be chased by heavily-armed intergalactic space whales? Most of us regular-types shy away from extreme violence in our everyday lives, which makes writing action-packed movies tricky, if we are strictly sticking with what we "know."