There's a lot to learn in life, and when possible, it's best to quickly learn from others instead of painstakingly learning on our own at the School of Hard Knocks. If you want to learn about making money, consider picking up some tips from those who seem rather good at it: billionaires.

Here are seven ways billionaires put their money to work, making more money. You can put some or all of these strategies to work yourself.

A hand is holding a huge magnet, which has pulled lots of U.S. currency toward it.

Image source: Getty Images.

No. 1: Don't fear failure

This bit of advice for getting wealthy comes from someone who has been a billionaire but has also given away so much money that she may not be a billionaire any longer: J.K. Rowling, author of the Harry Potter books. In a commencement address at Harvard in 2008, she said:

You might never fail on the scale I did, but some failure in life is inevitable. It is impossible to live without failing at something, unless you live so cautiously that you might as well not have lived at all -- in which case, you fail by default. Failure gave me an inner security that I had never attained by passing examinations. Failure taught me things about myself that I could have learned no other way. I discovered that I had a strong will, and more discipline than I had suspected; I also found out that I had friends whose value was truly above the price of rubies.

Steve Jobs echoes that, having said, "I'm convinced that about half of what separates the successful entrepreneurs from the non-successful ones is pure perseverance."

No. 2: Start early

If you hope to become a billionaire -- or even just a millionaire -- it's best to start early. Warren Buffett, for example, bought his first share of stock at age 11. It's probably too late for you to start that early, but you should still aim to save aggressively for your retirement, remembering that your earliest-invested dollars have the longest time in which to grow for you. Check out how a single $10,000 investment can grow over time:

After...

$10,000 Grows, at 8%, to...

10 years

$21,589

20 years

$46,610

30 years

$100,627

40 years

$217,245

Calculations by author.

A paper airplane made of a folded hundred dollar bill is flying forward.

Image source: Getty Images.

No. 3: Favor index funds

Don't assume that you have to somehow find the best stocks in which to invest and ferret out the best managed mutual funds. That's very hard, if not impossible, to do. Instead, consider the noble index fund. Yes, a broad-market index fund will just deliver the market's average return, roughly, but that can be quite powerful. The market has averaged annual gains of close to 10% over many decades. See how you might build wealth with a somewhat more conservative average annual return of 8%:

Growing at 8% For:

$10,000 Invested Annually

$15,000 Invested Annually

$20,000 Invested Annually

5 years

$63,359

$95,039

$126,718

10 years

$156,455

$234,683

$312,910

15 years

$293,243

$439,865

$586,486

20 years

$494,229

$741,344

$988,458

25 years

$789,544

$1,184,316

$1,579,088

30 years

$1,223,459

$1,835,189

$2,446,918

Calculations by author.

Know, too, that many billionaires greatly respect index funds. Warren Buffett has said that in his will, he offers these instructions for the money left for his wife: "Put 10% of the cash in short-term government bonds and 90% in a very low-cost S&P500 index fund. (I suggest Vanguard's.)" He's not alone, either. Ray Dalio, head of the massive Bridgewater Associates hedge fund, recently had almost 24% of its portfolio in SPDR S&P 500 ETF (NYSEMKT:SPY), and more than 21% in the Vanguard FTSE Emerging Markets ETF (NYSEMKT:VWO), which is invested in the biggest companies on the London Stock Exchange.

No. 4: Seize opportunities

Warren Buffett has famously guided investors to "Be fearful when others are greedy, and greedy when others are fearful." There are several bits of advice in there. For starters, it means not going along with the herd and instead thinking and acting on your own. It also reflects how great investors make many great investments -- by buying when the market has soured and prices are low, and often selling when stocks are overvalued and, therefore, likely to pull pack.

Hedge fund billionaire Sam Zell has reinforced this advice, saying, "When everyone is going right, look left."

A stamp is lying next to the word important that has been stamped in red.

Image source: Getty Images.

No. 5: Respect your circle of competence

It's also vital, if you want to do well investing, to know the limits of your circle of competence, and to aim to stay within it. As Buffett has explained:

What an investor needs is the ability to correctly evaluate selected businesses. Note that word "selected": You don't have to be an expert on every company, or even many. You only have to be able to evaluate companies within your circle of competence. The size of that circle is not very important; knowing its boundaries, however, is vital.

Lou Simpson, who invested many of Buffett's billions in the past, has said that, "Dealing in a circle of competence, dealing with companies that you have the ability to understand, being able to come up with a good analysis of a company's value and earning power, is fundamental." Similarly, Ray Dalio has noted, "Knowing you don't know something is nearly as valuable as knowing it. The worst situation is thinking you know something when you don't." And fellow hedge fund billionaire Seth Klarman has echoed, "Investors who confine themselves to what they know, as difficult as that may be, have a considerable advantage over everyone else."

No. 6: Start a great business

This last way that billionaires have put their money to work for them is not for everyone, but if it doesn't intimidate you too much, consider it: Start a business. Amazon.com's Jeff Bezos, for example, recently became the world's richest person, and his wealth stems from a little online business he started, selling books. Mark Zuckerberg started Facebook while still in college, just as Michael Dell started Dell Technologies.

Entrepreneurship isn't easy, but it can be extremely rewarding when it works out. You will be working for yourself instead of any annoying bosses, for one thing, and your schedule may be more flexible -- though many entrepreneurs work long hours.

Even if you don't start a billion-dollar business, you might still serve yourself well by taking on a side hustle, at least for a while. A side gig can bring in more cash, which can help you pay off debt faster or turbocharge your retirement savings. You might tutor kids or make furniture in your garage or do freelance writing or editing.

No. 7: Keep learning

It's also very effective to keep learning throughout your life, as the more you know, the better an investor you're likely to be. Warren Buffett's partner, Charlie Munger, has noted: "I constantly see people rise in life who are not the smartest, sometimes not even the most diligent, but they are learning machines. They go to bed every night a little wiser than they were when they got up and boy does that help, particularly when you have a long run ahead of you."

John Mackey, CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool's board of directors. Selena Maranjian owns shares of Amazon and Facebook. The Motley Fool owns shares of and recommends Amazon and Facebook. The Motley Fool has a disclosure policy.