In order to prepare efficiently for JNU entrance, you will need to study smart. Read the editorial and international relations page of Hindu and IE to get a fair idea of what is happening around the globe. Read Arihant’s guide for JNU entrance for IR. Rafer to some good magazines like Frontline, EPW, etc. 

The exam of JNU Entrance would be computer-based and Multiple Choice Questions would be asked. Make sure to study the following crucial portion of International Relations (IR). 

• Period of Cold War
• Treaties like CTBT, NPT, Kyoto Protocol
• United Nations
• Bretton Woods Institutions (IMF, WB, WTO)
• Environment Topics like Climate Change
• Indian Foreign Policy
• US Foreign Policy

The majority of questions in entrance will be from History, Economics, International Relations, Philosophy, Indian Politics, and Contemporary Issues.

Here are some books that you can refer to. 

• The Globalization of World Politics - Baylis, Smith & Owens.
• India after Gandhi - Ramachandra Guha
• International Relations in the 21st Century - Pushpesh Pant
• Global Politics - Andrew Heywood

Just prepare thoroughly without losing faith in yourself and be honest with your studies and you shall do well in your entrance. 

I have a friend who did his master’s from JNU and he was able to give some insight regarding the entrance test for MA Sociology. 

In the entrance examination, there will be questions from out of the syllabus. You may be asked to give a sociological interpretation of the current situation, event, etc. So, stay updated with contemporary social issues. Here is a list of sections from where you can expect questions.

• Sociological Thought: Marx, Durkheim. Weber, Parsons, Spencer, Comte, etc.
• Research Methodology and techniques
• Indian Society: Poverty, Family, Kinship, etc.
• Society and polity
• Society and economy
• Technology
• Caste and class system
• Concepts like Globalization, Modernization, Sanskritization, and Localization.

Go through the list of topics assisted to you and make sure you prepare them thoroughly. As you can see the majority of the questions are from the syllabus itself.

One of my friends was selected for BA French at JNU a few years back and here are his tips on how to do well in the entrance exam. 

G.K: You should incorporate every little detail from Arts, Literature, Drama, Culture, Dress, Cuisines, Geography, Nobel Laureates, and more to become familiar with the language you have pursued.

Reasoning Skills: You should be proficient in solving several coding-decoding problems, especially alphabetical orders, blood relations, syllogisms, direction, and ranking tests.

English: It is equally important to be as strong in English as you are in other subjects. Various course areas, like the Basic grammatical Rules, Vocabularies, Reading Comprehension, and Passages should be on the tip of your tongue. For best results, you should follow the editorial and articles published in “The Hindu.” 

English includes a major marking scheme for all the other sections. Now, since an essay alone contains a scheme of about 20-30 marks, it is best that you practice writing ingeniously without using heavy vocabulary. JNU appreciates the artistry of innovation and it is best to keep their tastes intact. Simplicity is encouraged along the lines of critical thinking, at least more than sophisticated word formations. 

It is best to keep your thoughts perfectly aligned with the subject area, and not outside of it.