9 simple rules that will teach you everything you need to know about money

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It turns out, everything you need to know about mastering your money can fit on a three-by-five inch index card.

That's what University of Chicago professor Harold Pollack discovered through trial and error, after turning around his and his wife Veronica's financial situation, which took an unexpected turn when they started caring for Veronica's disabled brother. Their income fell, as Veronica had to leave the workforce, and their expenses soared, thanks to medical bills.

"Harold came up with the concept of the index card not as some academic experiment but as a practical solution to the kinds of urgent financial problems many of us encounter at some point in our lives," financial journalist Helaine Olen writes in "The Index Card," the book she and Pollack co-authored to further explain how the concepts on the original card outperform more complex financial strategies.

The coauthors made a few alterations to the original index card, but the overarching theme of simplicity holds true — as Pollack found while turning around his financial life, "The most important advice was embarrassingly simple."

Here are nine rules to follow to start building wealth today, as described in "The Index Card":

1. Save at least 10% of your income.

Getting rich begins with paying yourself first. More specifically, set aside 10% to 20% of your gross income (the amount listed on your paycheck before taxes are taken out), Olen and Pollack recommend.

"If you can put aside 10% of each paycheck, you will have more than one month's salary set aside in your first year!" they write. "As an added bonus, you'll experience a whole lot less financial stress and drama along the way."

You don't have to immediately start setting aside such a hefty chunk of your money. "Saving 10% to 20% is the ultimate goal, not something you need to achieve yesterday afternoon," they explain. "It's better to save 1% consistently than try and fail over and over again to save 10% to 20%."

Today, it's even easier to learn to live without a certain chunk of your income, thanks to technology. You can automatically deposit money from your paycheck and checking account into a retirement account, savings account, or other investment vehicle, removing the temptation to spend. If you never see it, you'll learn to live without it.

2. Pay your credit card balance in full every month.

"A third of us will pay the minimum almost every month, with another third sometimes paying the bill in full but also often paying, yes, the minimum," Olen and Pollack report. In short, a lot of credit card users are paying just the minimum amount, and as a result, losing a lot of money.

Most credit cards only require you to pay 1% to 3% of your balance each month. "That minimum payment amount listed on your statement is not a recommendation," they emphasize. "Unfortunately, all too many of us take this minimum payment as just that ... Paying the minimum when you can afford to pay more takes a lot of money out of your pocket and gives it away to the credit card company."

Interest rates vary depending on the card, but credit cards charge an average of 15% on unpaid balances. To get an idea of how costly this can be in the long run, check out this chart showing how charging $100 per year and paying the minimum would result in you paying thousands of dollars in interest over time.

"There is no better way to simplify and gain control over your financial life than by eliminating high-interest debt," Olen and Pollack write.

3. Max out your retirement accounts.

"When it comes to planning for retirement, playground rules apply — no do-overs," Olen and Pollack explain. "If you don't begin putting away money today, you will almost certainly regret it tomorrow."

Getting an early start on retirement savings will result in huge gains later on, thanks to compound interest, and will allow you to maintain your standard of living when you're no longer earning a paycheck. "Wait until your forties and it will be much harder," they explain. "Some analysts say you'll need to save more than a third of your salary to catch up."

Contribute to your employer's 401(k) retirement account if you have access (if you don't, you have other options) and consider putting additional money towards a traditional or Roth IRA, other retirement savings accounts that offer tax benefits.