What do you know?
Well, what does that mean, anyway: write what you know? Does it mean if you're a postal employee, you should only write about stamps and manila envelopes and everything you pen should be an epistolary novel? Does it mean if you're a serial killer with dreams of writing a heartbreaking love story that you should forget it and send in your memoirs as horror instead? Does it mean if you've never been to Middle-Earth you can't imagine an elf or if you've never believed in religion you can't write a character with faith or if you've never had lost a child you can't imagine that, too? If you're God does that mean you only get to write in first person omniscient?
It doesn't mean any of that. Write what's true to you. Write what's real to you.
If you write something sad, you must weep at every predicate.
If you write something horrific, you must cringe in terror with every comma.
If you write something comedic, you should laugh at your every wild simile.
If you write something romantic, you should fall as madly in love with your characters as they do each other.
If you write something sexy, you should be turned on.
If you write something painful, you should hurt.
What if you don't? Is it not good enough? What if you're writing a murder? Must you kill? If you're writing a love scene, should you write it on someone's bare naked back? If you write a unicorn, must you tame him and ride him and make him your friend first?
No, but you should know it so well, you should know the feelings of this so intimately that you feel as if you have done these things. If you're writing a scene from a point of view of a mad man, you should feel insanity in you. Do you have to be insane? No. But you should be able to imagine it.
And if you're writing a drunk or a crackhead, should you be drunk or on crack? No. Can it help? Maybe.
The imagination is a powerful thing. The Romantic poets believed in two imaginations. The conscious one that creates and the unconscious one that dreams. For some people, imagination can be more powerful than experience.
But if you can experience firsthand, why not take advantage of that? Why not?
Everything we experience is part of the creation of our creative selves. An artist draws from everything within himself or herself. The more experience you have, the more you have to draw on. Does that mean everyone with experience will be a brilliant writer? Fuck no. But it does mean that those who know how to use experience, to draw upon it, to take the feelings and events and mistakes and pains and pangs and happiness of their lives -- their art will be all the better for it.
If you can take something positive out of suffering, then do it, and use it to write something real.
If you're not moved by your own work, how can you expect anyone else to be? If you don't feel as if you yourself have lived as your characters, how do you expect anyone else to believe them? Write what you know. You may know a lot more than you think. And we keep on learning.
Death is only the beginning.