It was 11:15.

The meeting had started at 11:00, and there was still no sign of my boss, who was supposed to lead it.

The room was filled with 8 high-ranking managers, some making small talk, others busy on their laptops.

At 11:16, my boss, our CEO, finally arrived and kicked things off.

One of our company’s core values was Respect. Part of the detailed description - which we on the management team had carefully crafted over several iterations -read: “We respect each other’s time by preparing an agenda for every meeting and by arriving on time.”

Oh, the irony.

Why am I telling this story?

Not to discredit my boss (with whom I had a great relationship), but to show that we all make management mistakes - often without realizing it - that have a big impact on team performance.

Because of the CEO’s tardiness, this behavior filtered down through the company and led to a lot of frustration and all sorts of issues with morale and collaboration.

My boss broke his own rules - something I consider an unforgivable management mistake.

I’ve made countless management mistakes myself. I wouldn’t consider myself a great people manager (which is one reason I’m now a solopreneur, I guess).

That said, I do have more than a decade of experience building and leading data teams.

My People Management Principles

After I shared my Hiring Principles 2 weeks ago, I now want to share my people management principles, too.

For context: over my 17 years in data, I’ve mostly worked in fast-growing VC- or PE-backed consumer companies.

I believe my principles work universally, but you may need to adapt them to your specific situation - especially if you work in corporate environments.

Also, these reflect my personal values and beliefs. You might disagree with some of them - and that’s OK. My goal is to give you a framework you can build on, especially if you’re new to managing people.

Principle 1: Lead by example.

If you want people to be punctual for meetings, you need to be punctual yourself.

If you want people to sleep under their desks when trying to hit a deadline, you need to sleep under your desk, too!

You must follow your system and its rules without exceptions!

Principle 2: Celebrate your wins.
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I used to be really bad at that.

I always thought that no milestone was really important enough to warrant a celebration.

Or I came up with lots of other reasons not to celebrate:

• we were delayed in hitting the milestone
• the milestone didn't add to the big picture in the way we envisioned
• we suffered too hard while reaching this milestone

But over time I learned that teams grow stronger when they celebrate together regularly.

So, I made sure to set up a reminder every 3 months to find something worthy to celebrate.

Principle 3: Praise in public - criticize in public.

Public criticism is not everyone's piece of cake but it's consistent with my value of transparency. I believe in radical open-mindedness and in the importance of people knowing each other's weaknesses and owning mistakes.

I try to make people shine and publicly praise them for their achievements. I protect my team from outside forces. If my team f**ks up, it's my fault. I have no problem taking the blame publicly, but then I make sure to criticize the person who f**ked up right away so that other team members (but no outside forces) know about it.

Important note here: This typically only works if the whole company adopts this principle.

Principle 4: Hire slow - fire fast.

In 99% of the cases where I felt that something doesn't work out I waited too long to let the person who caused the problems go.

Address issues quickly and take action quickly if it doesn't work. One bad apple can make the whole basket go bad quicker than you might think.

Principle 5: Remind your team of the rules of the game.

Have regular retrospectives where the team can voice feedback and where you have a chance to remind people of how the system works - of what your team's vision, mission and objectives are.

The outcomes of these meetings can be used to adapt and improve the system.

I always make sure to have one-on-ones with my direct reports once per quarter and I also make sure that every team member has regular one-on-ones with their direct reports.

Principle 6: Make it fun.

Work should not always be fun but it has to be fun from time to time.

Make sure to plan fun activities with your team.

And make sure that THEY decide what fun is and not YOU.

Bottom Line

You’ve just read my principles. But here’s the real challenge: What are yours?

Good management doesn’t come from copying someone else’s rules blindly. It comes from defining your own: based on your values, your context, and your experience.

So here’s my invitation to you:

✅ Reflect: What kind of leader do you want to be?
✅ Define: Write down 3–5 core principles that will guide your management style.
✅ Commit: Share them with your team - or keep them as your personal compass, but live by them, every day.

It’s a simple exercise, but trust me: it’s powerful.

Because the worst mistake a leader can make?
Not having clear principles at all.

Cheers,

Sebastian

P.S.: I'm sharing these principles and ALL my frameworks from 17+ years building data teams all over the world in my Masterclass "Create massive business impact with your data team."

👉 Watch it here .