"Stocks, by just about every long-term valuation measure, are undervalued," says John Reese, who continues to recommend putting money to work in undervalued stocks.

In his Validea newsletter, he selects "undervalued" issues by using screens based on the investment strategies of leading investors such as Peter Lynch, Ben Graham and Warren Buffett. Here's a a look at four current buys in the oil sector.

Reese explains, "If you think you can predict investors' emotional states, or how an unprecedented economic crisis will play out, then go ahead and wait for the bottom. I suffer no such delusions, however.

"Rather than playing the risky game of bottom-calling -- which more often than not leads to investors missing the big initial push of a new bull run -- I'll continue to put money into undervalued stocks.

This post is part of a special annual report -- Top Stock Picks '09 -- in which TheStockAdvisors.com asked 75 leading newsletter advisors to select their favorite investment for the new year.

"Technically speaking, World Fuel Services (NYSE: INT) is a stock that has shown incredible strength by outperforming the broad market," says Bernie Schaeffer, who chooses the issue as his top pick for 2009.

In his top-notch trading and investing service, Schaeffer's Investment Research, he looks at the company, which provides fueling services to marine vessels in some 1,000 seaports.

"The company estimates it holds more than 10% of the global marine fuels market. It also provides 24-hour fueling service to aircraft at 1,500 airports in more than 160 countries.

"Its aviation fueling business focuses on serving small to medium-sized air carriers, cargo and charter carriers, and private aircraft. World Fuel Services also markets fuel and related services to petroleum distributors operating in the land transportation market.