In the twilight of her long life, Julia Child said, “I’d like to know more about butchering!”

The lesson therein: Never stop learning. As experienced a cook as she was, Child remained an open and curious student of her craft.

Figuring that no matter how much some of us eat out, we probably don’t know everything — and based on the frequent etiquette and other questions that come my way — I figured I’d take a break from serving you a review this week and dish out tips for upping your dining game instead. Because everything tastes better with a dash of confidence.

Glass acts

It has become a problem of global dimensions: wine drinkers holding their glasses the wrong way. Take a look at the photograph of the POTUS toasting François Hollande at the recent state dinner for the French president, and what you see is two world leaders cupping the bowls rather than holding the stems of their glasses. Quelle horreur!

(Martin Gee)

Issue No. 1: “Hands conduct heat,” says Keith Goldston, wine director of Range and Aggio restaurants in Upper Northwest. That can be a good thing if the wine is too cold, he says, “but usually it isn’t.” Just as bad, hands transmit oils and aromas. The lemon wedge you squeeze into your water can mess with the way you perceive wine when you grasp its glass by the bowl rather than the stem, which, a couple of inches away from the liquid, acts as a sensory barrier.

A note about swirling: Unless you’re an experienced sipper, avoid grand, midair motions with your wineglass. Better to keep the glass firmly on the table and make tight circles to kick up the fruits and alcohol within the bowl, Goldston says. Overdo the swirling, though, and you’ll miss the delicate floral notes, he cautions.

As much as he would like to see wine presented at its best, in a proper glass, Goldston says stemware is less important than the environment, company and food. As the master sommelier puts it, “I’ve enjoyed wine out of a Dixie cup.”

A lesson in linen

For something so soft and pliable, napkins can cause a lot of anxious moments for a restaurant-goer. A useful abbreviation to memorize is DDU. The napkin goes down (on your lap) when you’re seated; down (on your seat) if you excuse yourself during the meal and up (on the table, and neatly) when you prepare to exit.

Upscale restaurants sometimes “break,” or unfold, the napkin for a diner, and discreetly place it on a patron’s lap. If a guest leaves the table temporarily, establishments including CityZen in the Mandarin Oriental hotel either refold the napkin or replace it, depending upon how soiled the cloth is, says restaurant director Michael Chesser.

Germaphobes, relax: To minimize touching, servers there are taught to reshape the napkin using its corners.

Eat like a pro

Want to look like a connoisseur when you’re eating sushi? Don’t rub your chopsticks together, says Nobu Yamazaki, the owner of Sushi Taro in Dupont Circle. Better Japanese restaurants tend to offer utensils that don’t shed splinters, unlike the cheap pine found in some noodle shops. Lunch customers at Yamazaki’s retreat receive bamboo chopsticks, while dinner guests sit down to higher-grade cedar ones. “They feel great and smell wonderful,” the chef says of the latter.

A lot of sushi is made with a dab of wasabi inside, which is why Yamazaki never adds the fiery condiment to a dish of soy sauce. Although he’s not against the practice, he suggests restraint, mixing in a pinch of grated horseradish. “Don’t turn the soy sauce into a gravy,” in other words.

It doesn’t matter whether you eat sushi with your fingers or chopsticks. Both are acceptable. Where you sit in the restaurant is actually a more important detail. Yamazaki says he’s able to give personalized attention to customers at the counter, where he can see them, and subsequently tailor his food to the way it’s being eaten. If he notices a diner using chopsticks, for instance, he’ll make a firmer pad of rice to support the raw fish. And lefties get their choices arranged in a different direction on the plate than right-handed patrons.

As for the spoon that comes with the welcoming miso soup, “ignore it,” says Yamazaki. The Japanese know to cradle the bowl and bring the broth to their lips.

Out, damned spot!

Among a food critic’s indispensable tricks of the trade is a good dry cleaner. Few people are more privy to what I’ve eaten than the staff of Georgetown Valet, a branch of which exists on 13th Street NW. If only I could rush to them after dinner every night, maybe then my clothes wouldn’t resemble Jackson Pollock prints.

My secret weapon between visits to the cleaners is Tide to Go. It’s the size and shape of a Magic Marker, costs about $3 and does a deft job of erasing traces of salsa, barbecue sauce and red wine, among other hazards of my occupation. Elaine Cella, principal researcher for Tide, says the pen has been tested successfully on more than 30 stains, grape juice and ketchup among them.

“It’s really great on coffee,” she says. “That’s my personal stain.”

Lest this plug come across as product placement, I asked Cella what a diner without an instant stain remover at hand should do at the sight of a splash or spill. First, she advises, “wipe off the excess.” If you can’t remove a garment, treat the stain with club soda at the table. Otherwise, in a restroom, reverse the material and run it under water, to help “push out” the stain. Warm water is best for most stains, except for blood, which should be countered with cold water.

Complain with class

It’s fine to register a complaint with a restaurant; just let someone in charge know while you’re still there rather than later, and use honey rather than vinegar. Also, if a dish is truly not to your liking, “don’t eat the whole thing!” That’s the advice of Saied Azali, the owner of Perry’s and Mintwood Place , neighbors in Adams Morgan.

Bring any issue to the attention of the waiter first, then enlist a manager if need be. “Once you’re outside, there’s not a lot we can do,” Azali says. “People go on Yelp without even talking to us.” The restaurateur’s response to customers who aren’t satisfied by a dish is to remake it or get them something different. If those options are declined, Azali takes the dish off the check. Ultimately, he says, “we’re in the business of pleasing people.”

Azali has gone to expensive lengths to keep customers. After a woman who attended a Christmas party at Perry’s returned to retrieve the coat she claimed to have left behind — three weeks after the fact, and without a stub — the restaurateur shelled out more than $200 to replace the wrap.

One thing he doesn’t tolerate: “People who demand free things” to make up for an unhappy moment. “I won’t do it,” Azali says. “Let us offer a suggestion.”