The Italian diplomat who navigated the political hierarchy of 16th century Florence has surprisingly relevant insight for professional women—and men, too. “He took emotion and morality out of the situation and examined it like a chessboard,” she said.

Not all of Machiavelli’s moves apply. (Ms. Smith doesn’t recommend, as Machiavelli did, you kill the family of a vanquished foe to avoid retaliation plots.) But many other strategies described in “The Prince” can be useful to anyone open to facing persistent challenges with compromises and imperfect solutions, she says.

In a recent interview, Ms. Smith explained ways current workers can use Machiavelli’s lessons to their advantage. Edited excerpts:

WSJ: What’s an example of a time you would have applied Machiavelli’s advice to your career?

Ms. Smith: I found out that a male colleague who had fewer years of experience and was producing about the same amount that I was was making significantly more money—like $20,000 a year more—than I was. I went into my boss’s office with no plan and started crying. It was the worst possible approach.

I had every reason to cry. But if I had been more Machiavellian, I would have thought, “How can I use this information?” I would’ve gone in with a plan and said, “Listen, I know how much my colleague’s being paid. Obviously my pay needs to match that, given my years of experience.” I would’ve seen it more as an opportunity than just a gut punch.

People tend to associate Machiavelli with ruthlessness. You reject that dimension of his philosophy.

Machiavelli is definitely associated with evil, but as I was reading “The Prince,” the thing that struck me was that it wasn’t malicious. Ruthless, maybe. He just analyzed everything. “This is not a great reality. But if you’re in it, what do you do?”

Are there wrong ways to apply these principles?

Yes. The trickiest thing about writing the book was that some of the advice feels very outdated. One piece of advice [in the book] is to smile in a job interview if you’re a woman, people will respond to you better. That of course doesn’t mean you have to smile, it’s a recommendation.

But there comes a point when your identity is starting to get a little compromised and I would tell people you just have to see what feels OK for you. One of the people I talked to for the book, Dr. Tina Opie, found—and it rang very true for me—that when you act in a way that’s not authentic, you do take a hit. It does damage to you personally and emotionally.

How assertive should you be when you’re still a job candidate?

The way in which you are assertive is the key. Think about what your power is versus the company’s power. Are there millions of people lined up to take your job? Do you have very rarefied skills? It always comes down to getting as much data as possible. When you present data like that, it’s seen as less assertive and more like, “I’ve done my homework.”

There’s a lot of research that shows that if you introduce new elements into a negotiation instead of having it be a face-off about one thing, it’s much more likely to be successful. “I want $75,000, but I want this title. I’d really love to work on this project. I’d really love the month of August off. I’d really love to work from home on Fridays.” It pulls negotiation out of the emotional zone and into a much more analytical, conversational, more Machiavellian place.

The book focuses on women, but can men use this advice?

The workplace is not easy for anyone. Even if you are the most privileged person, it’s still competitive. A lot of men I have talked to have enormous amounts of anxiety around negotiating. It’s applicable to anybody who struggles with asking for more for themselves.

What’s the most important message from the book for job seekers right now?

In the 15 years that I have been covering the economy, I don’t think I’ve ever seen a period where workers had this much power. Companies are very eager to keep workers or hire them away. This could be a really important moment for people to ask for situations that will make them happy, in addition to money and title.

One of the things that’s kept so many women on the sidelines is not being able to balance child care and work. Now that the stigma around remote work is so much less, it’s a perfect moment for people to ask for whatever will make the job they want possible.

What job would Machiavelli have today?

He was essentially the secretary of state for Florence, but corporations have more power now than the government, I think. He would be a head of strategy for Google, because of all the personal information. He’d work with big data. You know—walk softly, carry big data.

Write to Kathryn Dill at Kathryn.Dill@wsj.com