We only need two, according to Buffett, at 2008 shareholder Q&A session (transcript at GuruFocus). Note Q5, WB answer, he noted the following two courses:
1) how to value a business;
2) how to think about stock market fluctuations.
I think the first one is obvious, all the accounting, financial and quantitative skills. The second, is less obvious, it’s more about psychology. Buffett’s sidekick Charlie Munger summarized in his Human Misjudgement speech. Buffett also said something like “be cautious when others are greedy; be greedy when others are cautious“. This is certainly not science or a rule can be applied easily. For instance, if one person bought SPRD last Friday (like yours truely), it fell more today.
I noticed Danbin, a China hedge fund manager admires Buffett very much, also has his own way. He is almost religous about holding his stocks these days, amid the recent big drop of China market. You can read this article at his blog to get a glimpse. I am sure many of his clients are thinking or asking to bail out.
Oh, well, whatever it works for him/her. The key is to make money in the long run.