If you're hoping to get your finances in order and grow your wealth, Kevin O'Leary, an investor on ABC's "Shark Tank" and personal finance author, has some straightforward advice: Harness the magic of compounding returns.
"When you're 21 years old, or 20 or 18 or 19 and you start putting aside 10 percent of what you make, you'll [have] over $1,000,000 by the time you're 65," O'Leary tells CNBC Make It. "If no one else is going to worry about your retirement, I want you to worry about it."
Here's how O'Leary advises doing just that.
First, you need money to invest. If you think you don't have any, think again, says O'Leary.
"The truth is, there is a lot of crap you don't need," O'Leary tells CNBC Make It.
So evaluate your spending, and if you're wasting money on extraneous purchases, save it instead.
"What I've learned to do, and what has really helped me in maintaining growth in my own personal investing is, anytime I pick up something I'm going to buy, I say to myself, 'Do I really need this?'" he explains.
"Because if I don't buy it, the money is going to be invested and make money every year for me while I'm sleeping."
For example, O'Leary brews coffee at home instead of buying it at a coffee shop.
"Do I pay $2.50 for a coffee? Never, never, never do I do that," he says. "That is such a waste of money for something that costs 20 cents. I never buy a frape-latte-blah-blah-blah-woof-woof-woof for $2.50."
He also says he has pared down his wardrobe to spend less money.
"I looked at my closet one day, full of crap I don't wear," he says. "Piles of clothes, and suits and sweaters and shirts." So instead of spending money on new outfits, O'Leary says he just wears 20 black suits, which match 20 black ties and 20 white shirts.
"It's my uniform, you see me wearing this all the time. Why? Because I save a lot of money doing this," he says. "I don't have to think too hard about what I'm going to wear every day."
O'Leary advises you funnel whatever money you can into investments that will grow over time.
"This is advice I'll give you no matter what age you are," O'Leary says. "When you make money, I don't care if it's a gift for your birthday present, or you have a job on the side, or you're scooping ice cream or whatever it is — you have to take 10 percent of your paycheck every two weeks and invest it.
"People say, 'I can't afford that! I can barely afford my rent!'" he continues. "But it's not true, you buy crap you don't need every day."
But another way to get started investing if you don't have a lot of money is with exchange-traded funds, known as ETFs, which O'Leary recommends. An ETF is a basket of different assets, and you can find ETFs that include all sorts of asset classes — stocks, bonds, commodities and real estate too. So they have the benefit of diversification, according to O'Leary.
"You should never have all of your eggs in one basket, you should never own just one stock," he says. "There are 11 sectors in the economy, things like energy, defense, technology and there are thousands of stocks."
Still, you'll need to do your homework on the assets that make up the ETF to be sure they are sound investments, he says.
"One of the problems that young investors should consider and be mindful of is that an ETF is only as good as what's inside the basket," O'Leary tells CNBC.
O'Leary founded a company that offers ETFs, called O'Shares ETF Investments, which specifically targets dividend-paying stocks. A dividend is money that a company pays its shareholders, typically every quarter. By investing in stocks that pay dividends, you can spend or reinvest the amount paid out by the company, without having to touch your initial investment, leaving it to grow.
It's a lesson he learned from his mother.
"My mom understood a very basic premise," he explains. "Never spend the principal, only the interest."
Like this story? Like CNBC Make It on Facebook!
Disclaimer: CNBC owns the exclusive off-network cable rights to "Shark Tank."