I would print these skills on a poster and send them back to a younger me 10 years ago.

Leonardo da Vinci was not a brilliant entrepreneur.

A painter, sculptor, engineer, architect, scientist, anatomist, and philosopher — da Vinci was a precocious polymath. However, he had a terrible track record in finishing his work: he constantly had to return the money he’d been paid.

Here’s the point: you don’t have to be the jack of all trades to succeed in business. You only have to learn a few things but do them incredibly well.

Looking back at ten years of running my tech startup, I now think that most of my skills I hardly ever used more than twice. Being a da Vinci CEO wasn’t the reason I raised millions for my startup and got it acquired by a market leader years later.

Instead, what really mattered were a few selected skills that made all the difference. I would print them on a poster and send them back to a younger me 10 years ago (I’ve actually created this poster — you can download it here.)

Let me share them with you because anybody can learn them.

Your words are your most important communication instruments.

The better you communicate, the more you’ll sell, and the faster you’ll grow.

Every pitch, email, ad, and post contains words. But words do not merely transfer facts from person A to person B. Powerful words connect people through emotions and feelings. Great stories inspire millions for your products and services. At the same time, dull, lifeless words will bore your team to death and leave your customers cold.

A few years ago, I started writing every day: public articles to share my experience and private journal entries to reflect on my lessons throughout the day. I also used writer’s tricks such as active voice, powerful verbs, and specific language in my emails and meetings.

What started as a hobby later transformed how I managed my business — helping me use the power of words to turn me into a more persuasive team leader.

You can practice writing every day, too.

Journal every evening to reflect on your lessons throughout the day. Publish articles to share what you’ve learned. Hone your writing skills with every email you send.

Read about writing.

Learn storytelling with psychological tricks from Lisa Cron. Learn from Stephen King and Jack Hart to write consistent and engaging emails and posts. Infuse your texts with taste and flavor with Steven Pinker’s Sense of Style.

Writing not only teaches you to express yourself clearly and engage other people — but writing will also become an incredibly fulfilling workout for your mind, making you a stronger thinker and a wiser, confident entrepreneur.

When I founded my company, I was convinced that entrepreneurs must devise smart, intricate business plans surrounding complex products.

If products and businesses were too simple, anyone else would have already done it.

As you may have guessed, it’s actually the other way around.

Simplicity is one of the most essential and universal principles of every successful entrepreneur. It brings you speed, agility, and focus, according to Ken Segall — one of the creative masterminds behind Apple’s success, a man who put the “i” in iMac.

In my recent article, I explain how simplicity can help you succeed in two important ways.

First, simplify your products. Simpler products and fewer choices mean a happier frame of mind for your customers. So focus on doing just a few things, but do them especially well.

Second, simplify how you communicate with your customers and your team. Minimalistic communication makes your points stick better. Use simple and clear language.

My designer taught me a trick: never be afraid of white space.

In my early founder days, I used to see ads as real estate — a space that must be utilized at every inch. So I crammed our flyers and banners with information and visuals. But this is not how communication works. Design your ads to feel light and simple, don’t cram them with content.

And when in doubt, simplify again.

Entrepreneurs must strive to help make our world a better place besides filling their pockets with dollars. Companies are important to their employees, customers, and communities.

But in the end, the value you create for the world comes down to how many people are prepared to pay you for your products and services.

Revenue is the ultimate measure of your value in the world of business.

Besides, money is the oxygen every entrepreneur needs to keep going. It lets you hire more people, create better products, and viola: eventually build a better world.

But money is picky about its owners. It prefers those entrepreneurs who follow “money-attracting” principles. Award-winning author Morgan Housel shares these principles in his Psychology of Money.

In my recent article, I’ve curated Housel’s most crucial lessons.

First, beware of your passion. Money prefers founders who analyze their company with an icy heart: those who can distinguish between profitable and non-profitable actions.

When I designed my first product, I became the victim of my own dreams. I was passionate about creating a product I believed the world wanted. But I failed to listen to what the market was telling me: my customers wanted a different product. It was a painful and expensive mistake that I encourage everyone to avoid as early as possible.

Your passion is of no use to the world if you cannot produce a viable business that feeds you, your shareholders, and your employees.

Second, don’t obsess over single super-success stories. The more extreme the success story, the less likely you can apply its lessons to your life. Replicating Steve Job’s success story has a lower winning chance than a national lottery. Instead, learn from many reasonably successful people.

Third, stay frugal and protect your cash. Watch your account as carefully as scuba divers watch their oxygen tanks. Protect yourself from being wiped out or being forced to give up. Reinvest your earnings back into your business so it can grow.

WeWork’s founder, Adam Neumann, was a charismatic CEO who convinced his investors to pump billions into his startup.

Neumann eventually brought his company to a titanic collapse, burning roughly 40 billion dollars of market value.

In the Cult of We, the authors describe Neumann as an ambitious, flamboyant, and self-aggrandizing founder with a messianic complex. He created a company culture that punished people who disagreed with him, effectively making him the dictator of his WeWork empire.

WeWork’s founder gagged all voices that could’ve saved him and his company.

Don’t repeat Neumann’s mistake. Listen to other people and let them disagree with you. Remain confident but humble.

You are out there, confronted with a myriad of competitors and millions of customers — you alone don’t have all the answers. So listen to the voices of the market, to people around you, and especially — to your team. Every critique is an opportunity to learn, explore, improve, and succeed.

Humility also means self-reflection.

Every evening, after I tuck my kids in their beds, I sit down and reflect on my day. I write about the moments when I should’ve controlled my anger and other moments when I should’ve been pushier. I will probably never become a perfect leader, but I will keep trying to get better each day.

Call it the deliberate practice of life. It’s simple yet incredibly powerful: take a few minutes every day and listen to what the world is trying to tell you.

Three years after I founded my company, I ended up in a hospital.

The doctor standing near my bed asked me: “What do you do for a living?”

“I am a tech entrepreneur.”

The doctor smirked and suggested that I look into improving my work-life balance if I want to live until my forties.

Burnouts don’t happen because we work too much. They happen because we work with the wrong mindset.

My problem was: I worried too much about the outcomes I couldn’t control. I couldn’t sleep because I was scared to death of missing our sales targets. I yelled at my team when they failed to come up with creative solutions. My life felt like a huge dashboard with thousands of buttons I hastily needed to press to keep everything under my command.

One day, my brain short-circuited, and I collapsed on the floor in my office.

Trying to control the things you can’t control is among the dumbest things humans do.

Over two thousand years ago, the Greek philosopher Epictetus, the teacher of the Roman Emperor Marcus Aurelius, wrote: “Some things are in our control and others not. Things in our control are opinion, pursuit, desire, aversion, and, in a word, whatever are our own actions. Things not in our control are body, property, reputation, command, and, in one word, whatever are not our actions. The things in our control are by nature free, unrestrained, unhindered; but those not in our control are weak, slavish, restrained, belonging to others.”

Focus on the things you can control — your own thoughts, actions, and words. Then no one will ever compel you or restrain you.

So here is my last piece of advice. Repeat this serenity prayer when you feel overwhelmed:

“Father, grant me the serenity of mind to accept that which cannot be changed; courage to change that which can be changed, and the wisdom to know the difference.”