Learn to be long-term greedy when others are short-term fearful.

The bullish lesson?
Learn to be long-term greedy when others are short-term fearful. Going against the herd is never easy, but if you truly believe in a company's long-run demand story, major downturns can offer the very best buying opportunities. 

As Warren Buffett reminds us, "Only those who will be sellers of equities in the near future should be happy at seeing stocks rise. Prospective purchasers should much prefer sinking prices."

The bearish takeaway? 

There's just no substitute for knowing a business model cold.  The only way to reasonably predict a company's fortunes is to know exactly what sort of strategies management is pursuing, and questioning if they can actually create value by doing so.

As Buffett once wrote, "Equity Investment Strategy = Evaluate the Business in Its Entirety."

The final Foolish move
Investors often focus strictly on stock price movements, without realizing that developing a proper stock-picking process counts most.

http://www.fool.com/investing/general/2010/03/03/tuesdays-hottest-stocks.aspx