Facebook's lead HR consultant says these are the 3 most common mistakes new managers make

When the management guide "First, Break All the Rules" was first published in 1999, its main message lived up to its title.

HR directors across the United States measured employee performance according to standardized traits, and those deemed the best employees were well-rounded and always improving their weaknesses.

But according to the book's coauthors, then-Gallup analysts Marcus Buckingham and Curt Coffman, the best managers had employees embrace their strengths and ignore their weaknesses.

It was a bold claim in the world of management, but Buckingham and Coffman based their findings on 25 years' worth of Gallup studies of 80,000 managers across 400 companies, bolstered by research from Gallup psychologist Donald O. Clifton.

Today Buckingham is the CEO of The Marcus Buckingham Company, which coaches managers at companies like Facebook and produces HR software.

Business Insider recently spoke with Buckingham, and he told us that there are three mistakes new managers make most frequently as they adjust to their role. If they remain uncorrected, they can become deeply ingrained habits that can make both them and their teams miserable.

1. They assume everyone likes to be managed the same way they do

Buckingham fully supports Facebook HR chief Lori Goler's mantra of "one size fits one."

The first thing that Buckingham's coaches tell a new manager is that "each person has unique triggers that you need to trip" and that "you've got to be curious," in the sense that they must constantly pay attention to the individual needs and motivations of their team members.

"Unfortunately, these people don't have their strengths tattooed on their forehead, and actually are confused about what their own strengths are," he said. It's a manager's job to determine what it will take for an employee to thrive, and treat them accordingly.

2. They don't properly differentiate between strengths and skills

It's essential that managers understand what they can and can't change about their employees.

"You can't change their strengths, but you can change their skills and their knowledge, and you better be able to see the difference," Buckingham said.

Employees can always be taught how to do something new, and can learn more about a particular subject, including themselves. But their personalities and innate talents cannot change.

For example, you can teach employees how to be better communicators and collaborators, but you can't try to tone down someone who is naturally assertive, or try to turn an introvert into an extrovert.

3. They don't hold weekly, one-on-one check-ins with all of their team members 

Buckingham said that some new managers think a weekly team meeting is sufficient to bring everyone up to speed, but it certainly isn't. In fact, he argued, the best managers - regardless of their style, team makeup, or company - all share the habit of weekly check-ins with each employee they manage.

"That means every week you need 7-10 minutes with each person that reports to you, asking them just two questions: What are your priorities? How can I help?" he said, "because you have to coach or course-correct in real time. Don't wait six weeks to do it."

A common complaint his coaches hear from managers not following this is that they simply have too many people to manage. If that's the case, then either the manager is in charge of too many people, or they just aren't cut out to be a leader, Buckingham said.