"Write What You Know About"
I have always struggled with this piece of writing advice and I get disheartened when writers take it as gospel. Sure, I can see the merits of it in many instances. When you have been to the place that is the setting of your story, the writing will ring true. If you've slept on the 1,000 thread count sheets that your heroine swears by, you can describe the feeling with authenticity.
But there are times when this piece of advice is total rubbish. J.K. Rowling has never been to Hogwarts yet she managed to sell a book or two about a boy named Harry who went to school there. No one who has written about unicorns has ever been in the presence of one, yet they make for beautiful creatures in mythical stories. Humans still can't fly as far as I know, yet writers have witches taking to the skies on brooms. The writers of such stories have never been a thousand feet in the air with just a stick of wood holding them up yet they are able to write about the experience with gusto.
If you can imagine it, you can write about it. Don't stick to writing about things you have firsthand knowledge of if you are itching to do a story about the three-headed Loch Ness Monster.