The following things should be kept in mind for the entrance of M.A. in Political Science.

1. You have to be thorough with the exam pattern and syllabus.

You can refer to the JNU official website, there are previous year question papers provided on the portal. For the syllabus, you can refer to careers360 link: https://university.careers360.com/articles/jnu-exam-pattern

2. You have to have knowledge of current affairs and general knowledge. So work on the same because for the exam you need to answer in an in-depth manner.

To prepare for General Knowledge and current affairs, I recommend you the following; read newspapers such as The Hindu, Indian Express and Mint etc. Read magazines such as Frontline, Competition Success review.

3. Work on your writing skills for you need to write in a precise and in-depth manner. 

4. Practising previous year question papers is a must for entrance exams by doing this you get ideas on how to crack the exam.

5. You can refer to various reference books and booklets of previous year question papers, you can buy the same from Jawahar Book Centre, Ber Sarai.

I hope this helps. All the best.