It's not your imagination: The rich have been getting a lot richer.

The Congressional Budget Office reports that real income for the top-earning 1 percent of the population soared 275 percent between 1979 and 2007, compared with a 40 percent increase for the middle 60 percent.

There are various reasons for the widening wealth gap. One of them is that individuals with $1 million or more in investable assets, or an annual income exceeding $200,000, are considered accredited investors. This status has given them access to special investments such as hedge funds and private equity funds, which most investors don't have.

But while you may not be able to amass the personal wealth of someone such as Warren Buffett or Mark Zuckerberg, the average investor can grow and preserve wealth by taking advantage of any number of investing strategies that mimic those previously available only to the super-rich.

From mutual funds that replicate hedge-fund strategies to exchange-traded funds that invest in commodities, new strategies for the 99 percent have exploded in the marketplace, says Brent Fykes, senior investment partner at GenSpring, a multifamily office for individuals with at least $20 million to invest. "It's so much different than it was five years ago," he says. "And 10 years ago, it's like night and day."

The rich invest differently

But it's not just about adding a variety of investing strategies to your portfolio. There are two key concepts the 1 percent understand better than the 99 percent, according to Fykes: risk and diversification. Most average investors take on too much risk. "They tend to want to dabble in the stock market and buy the latest hot stock like Facebook or Apple," says Fykes. That strategy is dangerous because it leads to "all sorts of concentration risks," he adds.

The 1 percent, however, "by nature are less risky because they've created a nest egg and don't need it to grow at incredible rates," Fykes says. "They just want to stay rich. On the whole, the 99 percent is in the get rich mode."

For the 99 percent, understanding how to manage risk through diversification is key, agrees Katie Nixon, chief investment officer for personal financial services at Northern Trust. "What we typically see in the 99 percent is a relatively undiversified portfolio with a hodgepodge of funds and investments but lacking in overall strategy."

She recommends average investors match their portfolio with their financial plan instead of assessing investments on a one-off basis. Broader exposure to different asset classes for the 99 percent is a positive development, she adds, "but the key is figuring out what every strategy does to your portfolio and if it gets you to your goals."

Step 1: Inventory your assets

"The very first thing I would tell the 99 percent to do is to take an inventory of assets, and see what you have," says Nixon. "Build a balance sheet." She then suggests re-examining your goals.

Typically, there are four goals.

Family, which might include a wedding or education for a child.

Lifestyle, or your day-to-day expenses.

Capital assets for relatively short-term needs such as a car or a second home.

Philanthropy.

"Quantify your goals, and match each of them to an investment strategy," she suggests. "This is what the 1 percent does. Granted, they have very qualified financial advisers, but anyone can do this."

Step 2: Diversify your portfolio

Risk management through diversification is important in both maintaining and building wealth, but many investors think they're diversified just because they own a dozen different mutual funds. However, if most of the funds invest in the same asset class, such as large-cap stocks, the investor is exposed to risk.

"Since the financial crisis, we have seen many asset classes move in higher correlations with each other that differ from their historical norm," says Matthew Tanner, financial adviser in private wealth management for UBS Financial Services. Assets are considered correlated when they move together in relation to the mean. So if all asset classes are moving in the same direction, such as those made up primarily of stocks, your portfolio is not diversified.

"You need some assets to be zigging while others are zagging," says Nixon, who counsels clients to include assets across all capital markets in their portfolios. In addition to stocks, those could include some publicly traded real estate, commodities, high-yield bonds -- all of which can be bought through funds and will decrease the portfolio's overall risk. "For example, one of the biggest risks is long-term inflation risk," she says. "(Treasury inflation-protected securities) and commodities provide explicit inflation protection."

Nixon cautions that when investors are building a diversified portfolio, they should beware of the three factors that take away from nominal return: taxes, fees and inflation. "The first piece of advice I would give the 99 percent is to manage your fees."

Just because the 1 percent invest in hedge funds, for instance, doesn't mean average investors should look for funds that mimic that strategy, says Nixon. "If you want risk management, there are cheaper ways to get it than by adding a mutual fund that replicates a hedge fund. For example, adding high-yielding, dividend-paying stocks or certain fixed-income products."

Depending on individual risk tolerance, Fykes suggests an investor with a traditional portfolio made up of stocks, bonds and cash consider adding a possible allocation of 5 percent to 10 percent in commodities such as gold; 5 percent in a real estate investment trust, or REIT; 20 percent to 30 percent in long/short, market-neutral or arbitrage funds; and 20 percent to 25 percent fixed-income that goes beyond Treasuries and traditional bonds, such as global, emerging market debt, high-yield and TIPS.

The 1 percent don't necessarily have any secrets that the 99 percent can't copy, according to Fykes. Once you understand diversification and your risk tolerance, take the time for research, pay close attention to the U.S. and global economies, don't chase returns, and pay attention to more than just past performance.