The last in a three-part series on the fundamentals of wine appreciation.

I have solicited advice from many wine merchants over the years. Thanks to their guidance, I’ve found marvelous bottles I might otherwise have overlooked—and avoided some truly bad stuff. For the final lesson in my introduction to wine, I thought my student, Julian Pecht, needed to connect with a wine merchant that he could depend upon, too.

Because Julian is a resident of New Jersey, I chose a merchant there whose opinion I’ve often sought: Donna Garvey, wine team lead at Gary’s Wine & Marketplace in Wayne. (Proprietor Gary Fisch also owns a wine store in St. Helena, Calif., and another wine store in New Jersey; his wife owns two additional New Jersey locations.)

Donna (I’ve known her too long to call her Ms. Garvey) has been a reliable source of under-the-radar finds. Today she would demystify the wine shopping experience, I told Julian when we met up near the store’s large cheese section. Holding tightly to his notebook, he looked a bit overwhelmed by the 24,000-square-foot store offering not only wine and cheese but also glassware and all manner of wine paraphernalia.

“ ‘Let’s say I go into a store and tell them I want an Albariño. Is that just me taking a chance?’ ”

— Julian Pecht, 22

Donna’s first piece of advice to Julian: “You need to find a store where you can get to know the people and they can get to know you.” One of the best ways Donna can quickly assess customers’ preferences, she said, is to ask them to taste a few wines at the store’s tasting bar. That wasn’t an option, on the day of our visit, however; the Gary’s Wine & Marketplace tasting bar had been closed since spring 2020 as a Covid-19 precaution. (It has since reopened.)

Fortunately, Donna has another method of palate analysis. “I’m going to ask you a few questions,” she said to Julian. “How do you take your coffee?” Julian said he likes a latte but occasionally he’ll take his coffee black. “If you had to choose between green apples and pears?” Donna queried. “Pears,” Julian replied. “Are you a fan of black currants or plums?” asked Donna. Julian was ambivalent about both.

To Donna, Julian’s preference for lattes indicated he might like a wine with a richer texture. On the other hand, black coffee is more acidic, like some of the Rieslings Julian has enjoyed. If he’d said green apple instead of pear, she would think he might like a citrusy Sauvignon Blanc more than, say, a floral Riesling. Black currant and plum notes are associated with full-bodied red wines, “which I think are further down the road for him,” Donna noted.

Donna had one more question for Julian: “Do you prefer red or white wine?” He stated his preference for white, adding that he’d had some Rieslings he liked. We moseyed over to the Riesling section, featuring wines from Germany, Alsace and Austria. Donna made a game effort to explain Germany’s complicated Prädikatswein classification system; Julian looked a bit mystified by words such as Kabinett, Spätlese and Auslese. Helpfully, Donna repeated a tip from our first lesson: Check the alcohol level; anything 11% or above will be dry. I added that if he wants reliably dry Riesling, Austria is probably his best bet.

We turned to the shelf-talkers, aka sales cards, displayed with some bottles. Many used fulsome descriptors; some attached a point score as well. Julian asked how they decide which wines rate a note. “Anything Gary buys direct gets a note,” Donna said. A “direct” buy means Gary purchases a large amount of a particular wine. Affixing a card also depends on the wine’s profit margin. “As a retailer we don’t want to feature wines we don’t make money on,” she said.

We examined a few cards with numerical scores. The store only features scores from “credible” critical sources, Donna explained, citing publications such as Wine Spectator and the Wine Advocate. Other stores will feature numerical scores from unknown critics, Donna cautioned; store employees will even award scores themselves to wines they’re pushed to sell. This doesn’t happen at Gary’s, she emphasized.

Donna also warned Julian to scrutinize the vintage noted on the card to make sure it matches that of the bottle on the shelf. Lazy or unscrupulous retailers will tout a high score even if it’s for another vintage.

As we continued to make our way around the store, Donna counseled Julian that he should not “get stuck in one lane.” When she was just coming out of college, she recalled, a group of her friends got together once a month to try a particular type of wine; everyone brought a different bottle in the $10 range. “Then we all picked the winner, and whoever brought the winning wine got to pick the wine for next month,” she said. “It’s a fun way to expand your horizons.”

“The wines might cost more like $15 or $20 today,” I pointed out. This prompted Julian to ask, “Is the markup on wine random?” Donna explained that national brands are marked up the least because there is such fierce competition among them. Some are even sold at cost.

Donna led us to a section of the store where she said some of the best deals can be found: the wines from Spain and Portugal. She added that these countries offer some particularly good value in their white wines. She is quite keen on Spanish Albariño, a reliably good white she believed would fit Julian’s palate profile. “It has more texture than Riesling but not as much as Chardonnay—taking it one step at a time,” Donna explained. She offered Julian a taste of the 2019 La Caña Albariño ($15), noting that it has the pear notes and bright but not extreme acidity he had expressed a preference for.

Julian wasn't entirely confident he could replicate such a selection: “Let’s say I go into a store and tell them I want an Albariño. Is that just me taking a chance?” If there wasn’t someone he knew and trusted in the store to advise him, Donna said, he should look at vintages. You want a bottle that hasn’t been lying around; an Albariño shouldn’t be more than one or two years old. And if the bottles are dusty, shop elsewhere. Above all, Donna advised Julian to enjoy the process. “People come in and sometimes they’re almost tense,” she lamented. “I say, Relax, this is fun. We will get to the bottom of what you like. Don’t overthink it.”

As we departed, Julian returned to Donna’s idea of gathering with friends to taste wine. “It sounds like fun,” he said. “I always drank wine really passively before. Now I know enough to be curious.” I counted that as a victory. After all, curiosity is where all learning begins.

Email Lettie at wine@wsj.com.