I am Advocate Mohsin Ehsan During my LL.M in Punjab University following were my subjects

Int. law and economics
and
Administrative law
amongst many others.

the thing i felt as int.law for css is that, do not use that sub standard guide named khuram qurashi, that usually law students study.

Go for latest foreign books which are up to date i.e

for theory PUBLIC INTERNATIONAL LAW By Timothy Hilear 1999 edition
for case laws International law By Marten dixon

these books are available in Punjab University law College library.

One thing i should mention here that LAW OF SEAS is not usually taught in LL.B course of int. law. so i recommend all the students to study that portion. 90% objective is made out of it in css exam for int. law.

plus give small examples of international events in your question.

example: Topic ASYLUM ------> EXAMPLE IS, ON 28TH mARCH 1954 A CONVENTION ON TERRITORIAL ASYLUM WAS ADOPTED AT CARACAS.

Topic Extradition----------> example, In the reign of Zia several Political workers of pakistan People Party settled in different countries of Europe.
etc like that

hope u got my point.