Stephanie Danler has one piece of advice for the thousands of 22-year-old men and women moving to New York City each year despite the lack of entry-level jobs: Get a gig in the service industry.

“Any time you have the ability to take a job with that time-to-money ratio, where it’s in your favor and you can maintain some quality of life, you should take that job,” advises Danler, now 32 and splitting her time between Los Angeles and NYC.

Of course, she knows a thing or two about starting from scratch in the Big Apple.

As a 22-year-old in 2006, she moved to the city straight out of Kenyon College in Ohio. Unlike so many men and women who move to the city with big dreams, Danler’s plan was much more straightforward: To work in restaurants.

“I didn’t move here to become a writer,” says Danler.

“I had parts of a novel I thought would be easy to finish, but I’d been working at restaurants since I was 15. I knew that’s how I’d support myself. What I didn’t realize was what an intense and professional experience it was.”

She landed a coveted serving gig at Union Square Cafe, the Danny Meyer-helmed staple. It was this experience in the trenches of the NYC service industry — a total of nine years spent at Union Square Cafe, Buvette, Tía Pol and two wine stores — that found its way into her new novel “Sweetbitter.” Danler attracted a lot of buzz last spring when she sold the novel to Alfred A. Knopf with a two-book deal and an advance in the high six figures.

“Sweetbitter” tells the tale of Tess, a 22-year-old who comes to the city and works at a thinly veiled Union Square Cafe. It perfectly captures the raw possibility of a young woman’s first year in New York, opening up to a whole new world of wine, food, love and heartbreak.

And even if you don’t plan to pursue a career in hospitality, working in the service industry can teach you lessons far beyond proper silverware placement and how to navigate a wine list — lessons that will serve you well in any future career.

Here are the top four lessons Danler learned over the course of nearly a decade tending to others.

Handling difficult customers is the perfect training for dealing with future bosses and co-workers. “I think that so much of the service industry says, ‘The customer is always right, let me make myself small for you,’ ” says Danler. “But really, what it taught me was when to say enough, and no. The first time, finding your voice is scary and it gets really scary — with customers, co-workers, peers. It’s the lesson of my 20s.”

While women may have a hard time saying no, they have no problem saying sorry.

“Women in general spend a lot of time apologizing when what they mean is, ‘Excuse me.’ When I was managing restaurants, I tried to encourage my staff to be deliberate with their words and be mindful of that. The words become self-fulfilling.”

“Danny [Meyer] has this concept of hiring ‘51 percent’; 49 percent is mechanics, 51 percent is something you can’t train for. As I understand it, at the end of the day, it’s empathy: the ability to empathize with other humans quickly, to establish trust,” says Danler. “It allows you to do your job quickly, to anticipate quickly. Taking that outside of the restaurant, it’s something that turns into a lifestyle and a character trait. You can practice it. Sometimes you fail, sometimes you succeed. But his awareness of it was incredible training for me.”

“So I’m taking this from Danny, and this is his first tenet. It comes before taking care of the guests or the business,” says Danler. “That ethic applied to my real life is to take care of myself, and that will trickle down in the same manner to others. And that’s shockingly hard to do, especially in NYC.”