Source: Flickr user Ervins Strauhmanis.

The most certain thing about the stock market may be its uncertainty; but over time, there's arguably no better way for average Americans to get rich than by investing in stocks. If you're hoping that your stock portfolio can make you rich, you might want to consider these strategies from our Motley Fool experts.

Dan Caplinger: One time-honored way to build long-term wealth in the stock market is to focus on stocks that have long track records of steadily increasing dividend payouts. Companies that can sustainably boost their dividends at regular intervals have demonstrated that they have a leg up on their competitors, as they're able to survive inevitable cyclical downturns in their respective industries without forcing shareholders to share in their pain. The financial discipline that it takes to keep raising dividends also bodes well for other aspects of corporate management, suggesting that the company will be responsible in its other financial matters.

One great example of this phenomenon is tobacco giant Altria Group (NYSE:MO), which has been one of the top-returning stocks of the past half-century. Through thick and thin, including litigation threats, large settlements with government regulators, and rising excise taxes on its products, Altria has nevertheless managed not only to boost its payouts, but to keep yields well above the market average.

Time and time again, Altria has proven naysayers wrong, and even after years of falling cigarette volumes, the company has used its pricing power to sustain revenue and have enough cash flow to keep rewarding shareholders. Not all dividend stocks are as powerful as Altria, but many have what it takes to bring riches to patient investors.

Todd Campbell: As Dan points out, owning companies that pay increasingly higher dividends can be a wealth-building move; but investors might not want to ignore high-growth innovators either. Companies that can disrupt long-standing business models with next-generation solutions can significantly boost account values over the long term, too.

For instance, when Motley Fool co-founder David Gardner recommended Amazon on Sept. 9, 1997, he didn't have decades of financials to analyze. Instead, he took a calculated risk that Amazon would revolutionize retail.

Gardner has made similar bets on other high-growth innovators over the years, including in top performers Priceline and Netflix. While innovators like these suffered their fair share of setbacks as they grew, investors who were willing to take the long view have been handsomely rewarded.

That suggests that investors should be on the lookout for the next generation of innovators. Spotting them won't be easy, but a good place to start could be focusing on companies with products that you love that are led by visionary leaders.

Dan Dzombak: One way to get rich in the stock market is by taking advantage of a 401(k), particularly if your employer matches contributions. This investment option allows employees to contribute up to $18,000 a year -- $24,000 a year for those 50 and over -- to a tax-advantaged retirement savings account.

While every company is different, most employers match some portion of their employees' 401(k) contributions. According to the Society for Human Resource Management, the most common matching program is now a $1-for-$1 match up to 6% of an employee's salary. This means that, for every dollar you contribute to your 401(k), up to 6% of your salary, an employer will contribute another dollar to your 401(k).

This is, in effect, an immediate 100% return on your investment, and is what makes a 401(k) a better retirement savings option than an IRA. Of course, you can have both an IRA and a 401(k), but if you're not taking advantage of your employer's 401(k) matching program, you're leaving money on the table. Assuming average market returns of 8%, a 100% match of your contribution puts you nearly a decade ahead in your retirement savings versus if you had just contributed to an IRA.

Getting rich is simple, but not easy. It's not easy to put away large amounts of savings each year, but by contributing to a 401(k) account with matching contributions, you can build up a nest egg that will provide for decades after you retire.