One way to develop a winning investment strategy is to examine a stock in your portfolio that's given you a big gain and dissect how you came to select it. Chances are, the strategy can be repeated, resulting in even more gains.

My chief task here at

TheStreet.com

is to manage the Stocks Under $10 service that assembles a portfolio from -- you guessed it -- stocks priced below $10 a share. One of our big winners in the portfolio is

DynCorp

(DCP) - Get Report

, a defense outsourcing company whose niche is in training police forces abroad. After we added DynCorp to the Stocks Under $10 portfolio back in November 2006, the stock price jumped 100% in seven months.

Now, not all of our stocks produced the gain that DynCorp did. (Our portfolio delivered a 14% return in 2007, compared with a decline of 2.7% for our benchmark, the Russell 2000. Please

click here for a free trial of the Stocks Under $10 service.) But DynCorp provides an opportunity to examine the strategy we used to select it, and from that, pass along some suggestions that you may use to select stocks for your portfolio.

It's wise to develop criteria to use as a screen to narrow down the stock universe. We (my assistant Larsen Kusick and I) do that routinely in our research for the Stocks Under $10 portfolio.

We initially look for three criteria: stocks that are not generally followed by the market and certainly not by a large number of analysts; stocks that have growth potential over the next one to three years; and companies that are normally out of favor with the general public -- which are not difficult to find, considering that these stocks are trading in the single digits.

Our final criterion is the most important: We use a common-sense approach that is not defined by the numbers or anything you will read in an analyst's report. When looking at stocks that trade under $10, seldom will you find a stock that has solid financials

and

long-term growth potential, so it's important to identify whether the reward is worth the risk.

For example, although the homebuilders were seen as buys by many pundits months ago based on book value, our common sense -- which included all the for-sale signs around the country and higher living costs -- told us that demand was clearly slowing.

Using our initial criteria, DynCorp was a gem. The company was not widely covered by sell-side analysts -- or not well-known by the Street. In addition, it was out of favor with the general public, given last quarter's earnings miss. The upside was that DynCorp had several catalysts -- including the potential for large government contracts, given our presence in Iraq -- that had the potential to loft its growth substantially.

More specifically, defense stocks were booming in 2006; our continued conflict with Iraq was creating major increases in the U.S. defense budget. However, DynCorp, as a little, unknown defense company, was not participating in the boom. In fact, DynCorp dropped to below $10 from its May 2006 initial public offering (IPO) price of $15 after reporting a less-than-stellar quarter.

Back then, the Democrats took over the House of Representatives and the Senate. Many believed that a troop withdrawal from Iraq would soon follow. Since DynCorp -- at the time -- received most of its revenues from the Middle East, analysts viewed the Democrats' victory as a headwind.

This news, coupled with a mediocre quarterly earnings report, where the company reduced its full-year guidance, pushed the stock sharply lower, but we believed that the public was missing the bigger picture.

DynCorp's niche was training police forces in the Middle East, and the company was more on the services side and less of a manufacturer of weapons. This was a huge positive, given that police forces would have to be trained in the Middle East in order for U.S. troops to return home. Also, military spending would likely be pushed into training and rebuilding rather than weapons, considering that the U.S. was past the heavy combat stages in Iraq.

When we analyzed the weak quarter before our recommendation, investors seemed more concerned with the actual numbers and less about the reasons behind the miss. For example, earnings and revenue were on the light end of estimates, but DynCorp's backlog and cash flow increased for the quarter. Also, growth from its three largest contracts continued to gain momentum.

Its balance sheet was rife with debt at the time, but the company had just come public less than six months before, and management had significantly reduced its debt balance over the past 18 months. The debt-to-equity ratio stood at 65% -- much higher than the industry average of around 45%. -- but with nearly zero capital expenditures and forecasts for substantial cash flow over the next year, the reward seemed far greater than the risk.

Next, we listened to the conference call for DynCorp and, despite the miss in earnings, we came away very impressed with management - specifically Herbert Lanese, DynCorp's CEO. Lanese is not a politically correct type of guy, and his responses to some questions from the sell-side analysts could be quite entertaining.

Lanese's focus is clearly on the longer term. His belief that DynCorp will be a significant beneficiary of future contracts due to the increase in defense spending was easily translated to anyone listening to the call. The interesting part is that hardly anyone was able to recognize it, because DynCorp was on few radar screens given its recent entry into the public markets and its limited coverage by a handful of sell-side analysts.

Following the call, we knew that DynCorp would be in the Stocks Under $10 model portfolio, but we wanted to get the best price, which sometimes requires patience. Sure enough, investment firm Wachovia downgraded the stock on Nov. 11 to neutral from buy, which pushed shares lower. Later that day, we used the selloff to initiate our position at just under $10.50.

Since our recommendation, DynCorp nailed a $4.6 billion linguistics contract from the U.S. Army, beating out

L-3 Communications

(LLL) - Get Report

, one of the major defense contractors. Also, DynCorp was one of three firms chosen by the U.S. Army for the $150 billion LOGCAP (Logistics Civil Augmentation Program) contract, an initiative for peacetime planning for the use of civilian contractors in wartime.

Lanese's long-term outlook was dead on, and shareholders have clearly benefitted. Today, DynCorp is still in our model portfolio, and the stock is up 125% since our initiation. We believe that shares could hit $30 during the next 12 months.

DynCorp is a Stocks Under $10 recommendation. Frank Curzio and his team assemble a winning small-cap portfolio, including alerts when they buy and sell, and a detailed weekly roundup that recaps their holdings, which also include Taser (TASR) , Xoma (XOMA) - Get Report, Sirius (SIRI) - Get Reportand China Direct (CDS) .

In keeping with TSC's editorial policy, Frank Curzio doesn't own or short individual stocks. He also doesn't invest in hedge funds or other private investment partnerships. Frank X. Curzio is a research associate at TheStreet.com, where he works closely with Jim Cramer and and writes

TheStreet.com Stocks Under $10

. Previously, he was the editor of The FXC Newsletter and senior research analyst for Greentree Financial, and passed his Series 7, 63 and 65. He appreciates your feedback;

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to send him an email.