Book excerpt: "What do people know who are able to exert influence and advance their careers? What is the secret that they understand so well? I would say that they grasp a very simple relationship: the connection between communication, recognition, and influence,''contends Dilenschneider, CEO of the public relations firm Hill & Knowlton, in this authoritative handbook on leadership strategies. He argues that heightened competition and corporate takeovers have created an extremely volatile and challenging business climate, and draws on his own experiences in coping with crises (e.g., the cyanide contamination of shipments of Chilean grapes to the U.S. in March 1989) by cultivating good relations with the ``iron triangle'' of press, government and special interest groups. Quality work and accountability, Dilenschneider stresses, are an executive's basic responsibilities, while open, ethical communication remains a crucial skill. Executive Program/Macmillan Book Club dual main selection; Fortune Book Club alternate. (May) -Publishers Weekly.