Four Ways to Double Your Money in Five Years

But there are good arguments for accumulating wealth even more quickly. College and health-care expenses are rising faster than the average household's income, for example, while increases in longevity mean that you'll probably need a bigger nest egg to fund your retirement. That's why SmartMoney has assembled a guide to help you step on the gas pedal, doubling your wealth in just five years. And as aggressive as our premise may sound, the steps we've zeroed in on are reassuringly realistic.

First Trust AMEX Biotechnology (FBT), which owns 20 top biotech firms.

PowerShares Water Resources (PHO), focusing on companies that provide access to clean, drinkable water.

SPDR S&P Semiconductor (XSD), offering exposure to a sector many investors think is undervalued.

iShares Russell 2000 Growth (IWO), which cashes in on small-cap success stories.

iShares MSCI Emerging Markets (EEM), a valuable play, since emerging-world economies will grow faster than the U.S. economy over the next decade.

Here's an example of how the math works: Say you buy a two-family home for $850,000, putting down 20%, or $170,000. (The big down payment boosts your odds of having positive cash flow.) Your annual expenses, including mortgage, taxes and maintenance, will run about 10% of the amount borrowed. But you can write off every penny, along with capital depreciation, and then get back in the black with the rent you collect. Based on national averages for rental income, your total operating profit on this hypothetical house after five years would be $55,116, or about 6% a year. Sell the building at that point, for $965,000, and you've doubled your money. And that's assuming the property's value rises 14% — very conservative, considering the housing market's average annual return of 6.1% since 1975. Crunch some real estate figures yourself here.

Of course, you don't need your own website to pick up extra money. To pick just one example, the growing population of retirees and young singles (i.e., folks with free time) is creating more jobs for one-on-one tutors. Instructors working solo can earn anywhere from $15 to $95 an hour teaching anything from academic subjects to sailing to jazz guitar. For tips on starting or maintaining a small business, click here

Next, take a trimmer to the monthly mortgage payment. The spreads in interest rates between fixed- and adjustable-rate mortgages are fairly narrow right now. But rates have been sliding, and anyone who recently locked in a mortgage stands a good chance of finding a better deal — even more so if they hold an adjustable loan that has reset to a higher rate. On a $400,000 mortgage, the difference between a loan at 7.5% and one at today's prevailing rates of 6.25% would add up to more than $20,000 in payments over five years.

One final thought: Healthy living is good for your bank balance. A recent study by the Center for Creative Leadership found that executives who exercise regularly scored better on a test of leadership skills than those whose butts never leave their Aeron chairs. Though the study didn't examine earnings, it's not hard to see how these marks could result in bigger bonuses and faster promotions. On another hot-button health topic, smoking, a separate survey found that smokers earn 24% less than non-smokers. But there's one vice you won't have to give up. According to a recent study in the Journal of Labor Research, social drinkers earn up to 14% more than teetotalers. Cheers!

For more ways to cut costs on daily spending decisions, click here.