The three most important books in the field of trading that I recommend to any trader who wants to develop their knowledge and skills:

Trading for a Living – Alexander Elder: focuses on the psychology of trading (dealing with emotions), money management, and trading systems.

Trend Following – Michael Covel: explains the "trend following" strategy and how profits can be made from rising and falling markets. Wikipedia

The Complete TurtleTrader – Michael Covel: tells the story of a group of traders (the "turtles") and how they were trained to become successful traders, with lessons on discipline and risk management.