Freeland had previously shared how she celebrated the end of the negotiations—by laying down on the floor of Prime Minister Justin Trudeau’s office. At the Fortune Most Powerful Women International Summit in Montreal on Tuesday, she revealed some of the tactics that helped her seal the deal.

“One of the most important things is to have the home team be united,” she said. “It doesn’t seem like that will be hard, but if you have the home team united you can achieve a lot. If not, it’s impossible to achieve anything.”

Her second tip? “Have red lines and know what they are, and really mean it,” she said. “The worst thing is to say you have a red line and not mean it.”

Freeland appeared at the Summit alongside Federica Mogherini, the high representative of the European Union for foreign affairs and security policy and a vice president of the European Commission. Mogherini, who was involved in drafting the Iranian nuclear deal, also shared a negotiating tip—a simple one at that.

“Smile,” she said. “This is confusing to men in negotiations. If you show that you’re soft and accommodating, they’re completely disoriented.”

It was a lighthearted moment in an otherwise serious conversation about what Freeland and Mogherini see as a increasingly inward-looking world.

“I’m a super optimist, but the state of the world today is not good,” Mogherini said. “We’re moving away from the assumption we had developed in Europe after the Second World War that making war—competing—was less good for you than cooperating.”

Following World War II, there was a “win-win” approach that emerged across the Transatlantic space, Freeland said. That didn’t pit countries against one another; if one succeeded, another wouldn’t be offended by it.

There was a sense, she said, “both within our countries and around the world that we were trying to be better and better; to be more liberal; to try to include more people.”

Now, she said, “there is a very real trend going the other way.”