"We discriminate among investments primarily by their relative valuation metrics; we buy only those stocks we find undervalued relative to their own trading history, their peers or that of the market in general," says value investor John Buckingham.

The editor of The Prudent Speculator explains, "Two such buys are Marathon Oil (MRO) and Tsakos Energy Navigation (TNP).

"Both stocks could be chosen as part of the foundation of a portfolio for new investors or for those seeking to diversify their holdings.

"One of the 'super five' integrated oil and gas companies, Royal Dutch Shell (NYSE: RDS.A) has a diversified portfolio of oil and gas assets around the globe," says international investing expert Nick Lanyi.

In High Yield International, he says, "As one of the more conservative plays on a falling dollar and a rebound in oil & gas prices, I am adding Royal Dutch Shell -- yielding of 5.8% -- to our 'Reliable Income' portfolio."

"The Amsterdam-based company's revenue is more gas-oriented than its other super-major peers; about 40% of production is natural gas.

"In addition, Shell is more focused on unconventional sources of oil and gas than most -- the company plans to derive more than 10% of its revenue from sources such as oil sands and liquefied natural gas by 2014. This coincides with Shell's long-standing reputation as an industry leader in technology and engineering.