TO: Angelina Jolie, Sean Penn, and Brad Pitt
FROM: Rob Long
RE: Planet Hollywood

Welcome to the fascinating world of foreign policy! It’s wonderful that Hollywood has taken such an interest in world affairs—the hotel lobbies and corridors of Davos have never been so glittering, and hotspots in Africa and the Middle East are sprinkled with stardust. Boffo kudos, as we say in the business.

The world, though, is a complicated and treacherous place. It’s impossible, really, to convey the pitfalls and booby traps waiting out there as you venture far outside the 310 area code. Playing to the lefty Academy Awards crowd is fine, but that instinct may get you into trouble in, say, Caracas or Pyongyang. If you say something that delights a Fidel Castro or a Mahmoud Ahmadinejad, chances are it’s going to go over badly back home—and for good reason.

Still, your success in navigating the ferociously competitive world of Hollywood is the ideal training for global activism. Think about it: The entertainment industry is characterized almost entirely by shrieking egomaniacs, psychotic dictators, money-losing operations, clueless bureaucrats, corrosive nepotism, enormous travel allowances, and fraudulent accounting practices—not unlike most large nongovernmental organizations, the World Economic Forum, and the continent of Africa. You are well prepared to succeed on the world stage. Just remember these five key points:

Try a Modified, Limited Bono: To be an effective advocate of anything—immunizations, Middle East peace, women’s rights, whatever—you must first decide what you’re not going to advocate. By entering the global fray, you’re effectively trading on your name and your...