I recently finished reading this book, 「同時通訳者の英語ノート術＆学習法」by 工藤 紘実 and I have to say that it was probably the best introduction to interpretation that I have ever read. While it is titled as a simple note-taking and study book, it is so much more than that. It explains a lot of the foundational skills of interpreting that I had to learn the hard way.
Upside: This book covers a lot of the basics of interpreting like- when and how to take notes, how to study as an interpreter, how to manage vocabulary, how to get jobs and maintain clients as a feelancer, and how to manage your own time and stress.
Downside: I do wish it had had a little more on how to gain background knowledge and how to study for a particular job, but that may be too far out of the scope of this book.
Conclusion: Go buy it now! (You can even on kindle!)