I think one of the best ways to establish authority, either as an author or for one of your characters, is to focus on the lesser known details. The things that only a scuba diver would know. Or that pizza joint that only a lifelong Brooklyn resident would know. Look for the things, or places, that are inherently intrinsic in something, and not obvious to an outsider.
Here are a couple of examples:
I grew up on a thoroughbred horse farm. It was a small operation, just my father doing all the work. Occassionally we might hire temporary help to pitch in during the breeding season. Maybe an extra groom to work the Fasig Tipton summer sales. But usually it was just my dad, recruiting my brother and me to muck stalls, bring in the mares at night, and fill up the feed buckets with sweet feed. Now, while any writer would talk about the smell of the horses, or the noises they make as they stomp in the stalls, only someone who had really been there could talk about the smell that stays on your hands for days after cutting the twine used to tie up straw bales. I struggle to describe this smell, after all these years of trying to capture it on the page, I still haven‚Äôt done it justice. But I can tell you that as a kid, after getting that smell on my hands, a whole bar of Lava soap couldn‚Äôt get rid of it. I‚Äôm still trying to get that smell on the page, but when I do, it will carry a lot more weight than someone who watched a documentary on horse farms and said ‚Äúthe horses stomped and snorted in anticipation of being released from the stall.‚Äù Any knucklehead who had seen The Black Stallion could say that.
Geography works the same way. A friend recently asked me to read his short story that featured a Russian immigrant. The characters misses her home and to illustrate this longing, my friend wrote a scene where she thinks about how beautiful Red Square is in the winter with the snow on the curved towers. Now, it was a fine scene but I know that my friend has been in Moscow, he‚Äôs lived in Eastern Europe and travelled widely in Russia. He knows other places, more individual places, sites and scenery that only a Russian resident would know. Anyone can go down to the local bookstore, look at a Fodor‚Äôs for Russia and say ‚Äúwow, that Red Square sure is pretty‚Äù but I doubt a real Russian would think so fondly about it. As someone who lives in Orlando what their favorite part of town is‚Ä¶ it‚Äôs probably not Epcot Center but rather some neighborhood bar or some golf course where they hit a hole in one.
Author and creative writing teacher Robin Hemley agrees. In his 1994 book Turning Life into Fiction, Hemley writes ‚ÄúIf you rely on the obvious and the stereotypical when writing from a point of view that‚Äôs not your own, about a place that‚Äôs not your own, you will not be successful‚Ä¶ Think of it as a test of your imagination. If you set a story in New York, don‚Äôt have your character stand in front of Trump Towers, arms over his head, yelling ‚ÄòYou crazy, wacky city! I love you!‚Äô If you write about New York, better to include lesser-known landmarks, a particular Korean grocery on Broadway or a dry-cleaner. The more particular and individual the details, the more believeable they seem.‚Äù
So when trying to establish authority, look beyond the obvious and find the things that only a real expert would know. This will add authority, credibility, and realism to your work.