I took the exam last 2015 so these tips might not apply to future exams. One should always be updated about the exam content and studying the background of the current Board of Examiners might give a clue on the subject emphasis of the exam.
These are the subjects covered for the usual 2-day librarians' licensure exam and their percentages:
Day 1
Management 20%
Cataloging 20%
Indexing & Abstracting 15%
Day 2
Reference 20%
Selection & Acquisition 15%
IT 10%
Total: 100%. Remember that the passing grade for each exam is 50% but your average for all the subjects should be 75% or more to PASS.
For Management, Reference, and Selection & Acquisition: It is important to cover the basic theory and theorists of each subject. One should be able to analyze situational questions in the library setting.
Information Technology. Study the basics but also try to be updated in the latest technological trends in computers, social networks, the internet, and libraries.
Cataloging & Classification. Study the main classifications of both Dewey Decimal and Library of Congress cataloging systems. Practical know-how in cataloging is tested.
Indexing & Abstracting. Study citation styles and indexing styles for different print and online sources. Practice analyzing and comprehending abstracts to determine what kind of abstracts they are and their main subjects. During my time, this exam looked like a test of reading comprehension, but recent examinees have said that their exam was very different.