If you want to get into Buffett's head, read his teacher's book. The student has expanded Benjamin Graham's philosophy but has never forgotten those lessons.

He once said he was 75% Graham, 25% Philip Fisher. So, read both. Both are available at Amazon. 

The Roger Lowenstein book is quite good:

Buffett: The Making of an American Capitalist 

Geez... Since when has suggesting someone read Mr. B's letter get you knocked down on ratings. Easiest way is to read,

The essay's of Warren Buffett: Lessons for corporate america

I would echo reading The Intelligent investor and Common Stocks, Uncomon profits (to bad the son fell from the tree). If you take the three things that he learned BG you will see you need to understand basic business strategy, accounting, and valuation. That is how you learn to beat Mr. Market at his own game.

Last, you might want to check out

Financial Statement Analysis, a practioners guide

and

Valuation: measuring and managing the value of companies

 BGF