<<Things to remember >>
Dates, Names (persons, places), Definitions, Quotations
Read each topic again and again as you can understand it well. Then write it and remove your errors by your own,
The Method of attempting a question and selection of questions or essay topic is most important in CSS and PMS Exams, try to take an analysis of each topic in the perspective of “PEST” analysis (PEST analysis stands for "Political, Economic,Social, and Technological analysis") then attempt it.
(Ref is http://en.wikipedia.org/wiki/PEST_analysis)
Paste a Large size of world Political Map on your front wall and give it time on daily basis.