Which region? - Indo/Asia-Pacific, MENA, CEE, Western Europe, North America, South America, Sub-Saharan Africa, ASEAN, etc

Also which aspect of policy - business law, military technology, cybersecurity, innovation, economic regulation, internal politics, developmental economics/poverty alleviation, etc

For books/papers, it's best to read content published by members of the top 50 think tanks - https://repository.upenn.edu/think_tanks/

For a lot of regions, you may need regional language fluency (eg. Japanese NatSec people prefer writing in Japanese, Korean NatSec people prefer writing in Korean, PRC NatSec people prefer Mandarin, Russian+Ukrainain NatSec people prefer Russian+German, West+Central Africa excluding Nigera NatSec people prefer French)