CHICAGO (TheStreet) -- As of May, Apple iPhone users were downloading more than 800 apps per second at a rate of 2 billion apps per month, ranging from addictive games to sophisticated tools for everything from video editing and road navigation to fitness trackers and finance management. But apps, whether for the Apple or Android platforms, are more than $1.99 accessories for your smartphone; behind each one is a company whose business model could be a productive complement to an investment portfolio.

Before investing in company making the latest (or next) app, consider these five tips:

Keep an eye on privately held companies.

Many software companies remain privately held, so despite the desire to invest in them, the opportunity isn't there yet. Many will ultimately go public (a notable example: Facebook), so keep an eye on IPOs and acquisitions.

One example of a promising, privately held app company is Waze. Its road navigation application has proven successful worldwide, and Waze was recently acquired by Google for $966 million. This app and its company's business strategy showed promise before its acquisition, and you should look for similar companies with strong investable qualities.

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Look for new and innovative publicly held companies.

On the public side, one app that stands out as a potential moneymaker is GlassesOff. Launched in December, GlassesOff is a neuroscience technology and products company that has developed a smartphone app aimed at eliminating the need for reading glasses. 

It uses patent-protected neuroscience exercises to improve image processing function in the brain's visual cortex. The user participates in "intensive visual stimulation tasks" for approximately three 12-minute sessions each week for three months. Once the program is complete, ideal users can expect improved image-processing capabilities that allow them to read up close without reading glasses. 

Consider the market and the app's reach.

Apps that reach only niche markets are less likely to be lucrative investments. Think broad when investing.

Waze and GlassesOff cast wide nets. As of 2009, there were 210 million licensed drivers in the United States, which creates a large market for Waze -- and therefore is the type of app that makes a smart investment. Similarly, most people over the age of 40 need reading glasses, making a potential market of more than 100 million people in the U.S. alone and more than 1.4 billion people worldwide.

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Consider the available platforms.

A solid app investment is usable by iPhone and Android platforms and on multiple devices, including phones, tablets and computers. 

GlassesOff, for example, continues to expand its reach from smartphones, having released its first iPad product Jan. 21. Since widely quoted industry figures say 38% of those aged 45 to 54 own a tablet, GlassesOff is now able to better serve its target demographic: adults in their forties and fifties. A company statement has promised an Android version for the second quarter of this year, targeting potentially hundreds of millions of Android-based smartphones and tablets consumers.

Accept volatility and risk in investment.

The app market can be somewhat intimidating, especially to novice investors, due to its newness and the volatility of companies such as Zynga, a developer of social and mobile gaming. But turnarounds are possible, and it's smart to consider improvements in the company's financials before selling; Zynga's revenue last year came in at $873.3 million, less than the $1.1 billion of 2012 but exceeding Wall Street estimates of $712 million. 

Remember, even as industries and technologies emerge and Apps are developed and launched at mind-boggling rates, the stock market will always be bulls and bears. Consider business models and promising qualities when investing in the young yet promising mobile app sector. Companies such as Waze and GlassesOff show utility and promise for growth within large markets, so stay diligently informed on what apps are launching and consider companies with similar qualities when investing.

This commentary comes from an independent investor or market observer as part of TheStreet guest contributor program. The views expressed are those of the author and do not necessarily represent the views of TheStreet or its management.