Inv: how to dig out great company in market?

http://finance.ifeng.com/money/roll/20110903/4524387.shtml

From this chinese version article, the suggestions from Buffett about how to invest $1M, is to go through every company in the market and filter out some great and under valued companies. Easy to follow? And, Buffett will prefer smaller companies to get higher return.
:( I tried but I can really read all companies' report. And, my previous conclusion, don't buy small companies, because the available information of small companies is hard to find, and big risk if I don't know the company.
So I think I will still follow some good and big companies, and buy only when price drops a lot, eg. >20%.