NEW YORK ( TheStreet) -- One thing that Jim Cramer always harps on to RealMoney readers and viewers of his "Mad Money" show is the importance of doing extensive homework before investing in any stock. Nowhere has this been more important than in the energy sector in 2013.

With the Dow reaching all-time highs and with energy being one of the strongest sectors in that rally, you'd think that any investment in energy would be a winner, but that's very far from the truth.

If you've picked right inside the energy sector, you've seen tremendous upside already in the new year. If you've picked wrong, however, you're seeing stocks slide to some of the worst prices they've had in years.

Have a look at the video above that I shot with Jim. It differentiates the good from the bad and stress the necessity of doing some very intense homework before picking stocks and buying them.

This article is commentary by an independent contributor, separate from TheStreet's regular news coverage.

Dan Dicker has been a floor trader at the New York Mercantile Exchange with more than 25 years of oil trading experience. He is a licensed commodities trade adviser.

Dan is currently President of MercBloc LLC, a wealth management firm and is the author of "Oil's Endless Bid," published in March of 2011 by John Wiley and Sons.

Dan Dicker has appeared as an energy analyst since 2002 with all the major financial news networks. He has lent his expertise in hundreds of live radio and television broadcasts on CNBC, Bloomberg US and UK and CNNfn.

Dan obtained a bachelor of arts degree from the State University of New York at Stony Brook in 1982.

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