This article is part of our Rising Star Portfolios series.

For my real-money Motley Fool portfolio, I've already invested more than $5,000 in the past five months. So far I've had a good amount of success, and one of the best practices I've implemented is to always have a watchlist -- stocks I'm watching closely that have caught my eye for one reason or another. Continuing to update your theses and ideas is one of the greatest ways to make sure you always have a home run idea in the works.

Below are three stocks that I'm watching carefully, and I suggest you do, too.

3 stocks for your watchlist
Banco Santander (NYSE: STD): This has long been one of my favorite banks, not least because of the company's 100-year history, tenured management, and fantastic dividend. It is the largest euro-denominated bank, managed to get through the 2008 financial collapse without so much as flinching, and used the downtrodden market to scoop up market share from the likes of BBVA and buy auto loans from Citigroup (NYSE: C). However, Spain's unemployment is sky-high, and many banks are fighting off declining profits and rising bad debt. Now that Portugal has officially asked for a bailout, many fear that Spain will be next. Typically I'd see this as a great contrarian opportunity to get a great bank at a cheap price (P/E is only 9.10); however, last year I bought shares of National Bank of Greece (NYSE: NBG) on a similar notion, and have only watched my investment tank. Not that I believe it was a bad purchase, but it's made me a bit more risk averse. I'll be watching the Spanish economy closely and trying to gauge how close or far away they are from being the next eurozone victim.

Covidien (NYSE: COV): Covidien develops and manufactures health-care products that range from medical devices to surgical instruments to pharmaceutical products. However, it's not trying to be like its biggest competitor, Johnson & Johnson (NYSE: JNJ), which is admittedly a behemoth. Covidien is carving a niche for itself with its minimally invasive surgical instruments, and it holds the top-4 market share in virtually all of its product lines. Now that it's been spun off from former parent Tyco International, it's been able to successfully invest in R&D and build out a solid product pipeline unhindered by capital constraints. Covidien is trading for a pretty reasonable P/E of 16.1, which is much less than it has averaged since its spinoff. A large part of Covidien's business was in safety syringes and needles, and intense competition from Becton, Dickinson (NYSE: BDX) will force Covidien to compete on price -- not something it really wants to do. I'll also be watching to see what the company will do with its pharma business, not really core to its operations, to see if it divests it or hangs on for other reasons.

IMAX (Nasdaq: IMAX): I'm still kicking myself for not buying shares of IMAX a few years ago when I remember saying to myself, "Nobody goes to IMAX theatres anymore!" Little did I know that 3-D technology would take off as it did and that multiplex theaters would come to depend on the IMAX experience to boost ticket prices and sales. The company has come off of one great quarter after another, and it recently expanded into China, signing a 75-theater revenue sharing agreement with Wanda Cinema Line, the largest theater chain in the country. Hollywood is behind IMAX, theaters are behind IMAX, and most importantly, consumers are behind IMAX. Despite five-year growth estimates of about 25%, IMAX trades for a P/E of only 20, pretty cheap by my calculations. I'll be watching to see if IMAX stumbles or if it continues on its quest for your movie viewing domination.

The Foolish bottom line
Consider these three stocks above and add them to your watchlist to get the latest news and commentary. By clicking here, you'll not only start your own watchlist, but you'll get free access to our brand-new report, "6 Stocks David and Tom Gardner Think You Should Be Watching."