Martha isn’t comfortable investing. She stuffs her savings into a bank account instead.

John gives his money to his broker. He’s too busy to think about investing and he really trusts the guy.

Lisa follows stock market news. She watches mutual fund lists and buys top-rated funds.

Plenty of people are like Martha, John and Lisa. But they’re making big mistakes that are easy to avoid.

Savings Accounts Lose Money Every Day

Banks love people who stuff money in their savings accounts. These accounts pay paltry interest. The rising cost of living leaves that interest in the dust. Meanwhile, the banks use their money. They say, “If you won’t invest it, we sure will!” They loan it out on mortgages. They loan it to people who are using credit cards. Banks earn a killing on that money every year. If you have a big balance in your savings account, the bank borrows money from you–practically for free. It loses value every year because inflation eats it up.

It’s OK to keep emergency reserves in a savings account. But adding sums beyond that represents a huge mistake.

Don’t Get Close To An Investment Broker

I once heard somebody say, “I put two kids through college–too bad they were my broker’s.” Few people wake up and decide, “I’m going to be become a broker to make the world a better place.” Those who want to give usually jump to different jobs. They join the ranks of teachers, nurses, and other public service workers.

That said, investment brokers are often the kindest people in the world. They sell their personality. That’s a trick to their trade. If they can buy trust, they can sell you almost anything. Investment brokers love to sell actively managed mutual funds. If they get really lucky, they might also charm you enough to sell a variable annuity. Compared to smarter alternatives, these take money from your future.

Don’t Follow The Markets Or Buy Hot Mutual Funds

Have you ever walked into a casino and seen the bells and lights-a-flashing? It promotes crazy thinking. It makes people believe that they can win too. Sometimes, somebody does get lucky. But as most of us know, they eventually give it back. The casino makes money. It’s rigged against the players.

Similar bells and whistles seduce stock market watchers and mutual fund investors. But at the end of the day, the casino makes more. That casino is the market. If you own the market, through a low-cost index fund, you’ll beat almost every player.

Much like the casino, the game is rigged that way.

Forget about fund companies that say they win long term.

Forget about investment magazines that tout the best funds to buy.

Forget about stock market conditions that require a skillful hand.

Here’s what you should do. If your workplace offers a 401(k), maximize deposits–especially if your employer matches part of your contribution. Saying no to free money is Norman Bates-crazy.

Not sure which funds to buy? Let me offer a suggestion. It’s based on common sense and reams of academic data. It lets you own that casino. If you can, also try to max contributions to your IRA. Choose Vanguard’s Target Retirement funds or another low-cost investment firm.

Building wealth is easy if you avoid these three mistakes.

Andrew Hallam is a Digital Nomad. He’s the author of the bestseller, Millionaire Teacher and The Global Expatriate's Guide to Investing: From Millionaire Teacher to Millionaire Expat.