I’ll probably have ten posts with the same title. But right now I’m feelin’ the best possible thing you could do is: read Foreign Affairs and The Economist cover to cover. All the time. Especially Foreign Affairs. You can find these at your library or purchase a subscription yourself; definitely read the past several issues of Foreign Affairs at the library.
There are other great foreign policy journals also. But here’s why you need to do this:
1. You Will Learn the Language. Benefits to your education, college applications, and life aside, by reading journals in the field you will begin to learn what the important issues of foreign policy are and the language used to speak about them. For example, once you learn that “legitimacy” is a key concept of what you may be searching for as “political capital”, your searches for evidence, book picks, and even your arguments will dramatically improve. This is true of neoconservativism, foreign policy “hawks”, or, as you want to search in the journals, “realism”. Neo-liberalism, liberalism, and marxism all have different meanings in the foreign policy context as schools of thought you need to know.
2. Okay, now the other benefits. Besides helping prepare you for the Foreign Service Exam (:-P), you will become a jedi knight of foreign policy issues. You can engage in and understand national discussions of foreign policy (typically an elusive topic for the high-school aged), understand how your studies fit in with international politics, and maybe decide whether this field is or is not for you.
[METAPHOR ALERT!!] If you immerse yourself in the major foreign policy body of knowledge on a regular basis, you will become a powerful debater able to slice through the media/populist language and concepts your opponents are dishing out.