Although he has been maintaining a cautious stance on the refining group, energy sector expert Elliott Gue is now boosting the rating on Valero Energy (NYSE: VLO).

In his The Energy Strategist, the advisor explains, "Valero is now attractive for three reasons: superior geographic exposure, refinery complexity and a new focus on profitability."

"Our caution on the refining group was due to expectations that crack spreads would be weak through the spring, a period during which spreads tend to widen. Overall, this call was correct: Refiners have underperformed the energy patch since mid-March.

"And longer term, I have some concerns about new refining capacity expansions due to come online over the next few years. As this supply comes online, it could put downside pressure on margins.

"But over the next six to nine months, the refiners look like a compelling play. Gasoline inventories are now back in line with seasonal norms; it's likely gasoline prices will now rally further relative to crude oil. In fact, we're already seeing an obvious spike in crack spreads.

Leo Fasciocco is a technical expert who focuses exclusively on finding breakout candidates. In his Ticker Tape Digest, he looks to agriculture equipment manufacturer Deere & Co. (NYSE: DE).

"Deere, with annual revenues of $24.8 billion, makes agricultural, industrial, forestry, and lawn-care equipment. DE is benefiting from the strong demand for its products in the farm sector. The company is also expanding aggressively in Russia.

"DE has broken out from a 13-week flat base. Its long-term chart shows DE soaring from 20 in 2003 - the start of the prior bull market - to 92. It has been a big winner in the big cap sector. The stock has gained 65% in the past 12 months versus a 5% drop in the S&P 500 index.

"The stock is in a base bracketed between roughly 78 on the downside and 91 on the upside. The breakpoint was set at the key upside resistance of the base. Deere has plowed through that resistance on increasing volume.

"Green investing and clean energy may be the politically correct topic at cocktail parties, but coal is the economically correct vehicle for investors," says Ronald Rowland and Brandon Clay.

The editors of All Star Investor explain, "Coal has been an energy source for millennia -- and is still the number #1 source of energy for electric power plants in the world." And, they add, "One of the best places to invest in coal is Consol Energy (NYSE: CNX).

"Prehistoric Chinese are said to have used coal for heating. According to Roman historians, Britain burned coal in the first century. Throughout history, coal has been the primary source of heat in homes.

"Rapidly industrializing nations like China are still dependent upon coal for energy. Overall global consumption has not diminished either. Coal fuels 48% of electricity plant generators. And the trend is heading upward – probably for the next 30 years. Despite the deafening rhetoric, coal is not going away anytime soon. Investors should take notice.

The New York Times recently made a case for investing in stocks to gain exposure to commodities:

But there is an easy way to get a shot at commodity-like returns, without investing directly in commodities or their indexes. Investors can buy shares of the natural resource companies that produce commodities.

However, investors need to be careful: just because a stock is in a sector related to commodities doesn't mean that it will move with the prices of those commodities. Other factors, including decisions by management, any hedging the company may have in place, and other company-specific factors, may cause their returns to differ from those of the underlying commodities. While it's quite true that, as the New York Times points out, natural resources stocks have outperformed commodities in recent years, that is not a trend that will necessarily continue.

There may be good reasons to buy these stocks, but if you want to make a bet on commodities prices, the best way to do that is with exchange-traded funds (ETFs). Back in his days at the Motley Fool, BloggingStocks contributor (who is the source for news and analysis for private equity, by the way) Tom Taulli wrote a nice piece about how to invest in commodities through ETFs.

If you really want to learn about ETFs, I recommend picking up a copy of Investing with Exchange-Traded Funds Made Easy: Higher Returns with Lower Costs -- Do It Yourself Strategies without Paying Fund Managers by Marvin Appel.