8. Understand the value of one buck.

Even in a society where mediocre singers can make $5 million a year, where a really bad financial advisor can still make $1 million a year, and where the price of Chicago Bears season tickets has gone through the roof... a dollar still holds more value than you think. How so?

Let's say you're 20 years old. Start with one dollar and add a new dollar of savings every week. At the end of each year, move that $52 into the stock market. Repeat this for every year until you're 65 years old. How much money will you have saved? $51,253. That's a lot of marbles for just putting one buck away each week. Imagine if you had saved five dollars a week -- you'd end up with $256,266. A quarter of a million dollars.

The above examples assume that your money is growing at the historical market average of 11% per year. But there are ways you can be more Foolish with your investing. The Dow Dividend Approach, for example, is easy enough for a nine-year-old to figure out, and has returned an annual average of between 16% and 20% for decades. If your five dollars per week grew at 16%, it would become $1.3 million. At 20%, it grows to a whopping $4.8 million.

Saving small sums of money regularly and investing them will open up a world of opportunities for you.

It will also allow you to battle through some egregious mistakes. That's right. As you develop into a savvy investor, you're bound to make some regrettable moves. Even Warren Buffett, arguably America's most impressive investor, has made some blunders, even when he was experienced. Mistakes are inevitable. But by sticking to Foolish principles of long-term investment in common stocks, you'll never lose your whole shirt. Yes, a sock or a cuff link here and there. But never your whole shirt.

Save and invest, Foolishly, a little at a time.

Step 9: Ignore the pros