I opted Philosophy in CSS 2012 this was my first attempt i don't know what will be the result......
I went through the past papers n i found 3 books which i felt relevant and can give u best marks
1: Introduction to logic by Irving M. Copi and Carl Cohen for paper 1
2: philosophy made simple by Richard H. Popkin, PhD and Avrum Stroll, PhD
and History of Muslim Philosophy both volumes
for paper 2( only Contemporary Philosophy part)
i can give u list of 12 questions if u prepare these both papers are done....
for paper 1
i: Logic and kinds of logic(with special reference to Aristotlian logic & Induction, Deduction, Argument, Statement, Definition, Truth and Validity)
ii: falacy
iii: Symbolic Logic
iv: Probability in Logic

for paper 2

i: Idealism(hegel, berkely and others)
ii: Dialectical Idealism & Materialism(Hegel's dialectics and Marx's dialectic)
iii: Existentialism
iv: Positivism
v: Pragmatism
vi: Iqbal's Philosophy & Sir Syed.
vii: Al-Farabi's Philosophy
vii: Ethics(A.J. Ayer's, Imannual Kant and others
short notes also come from these topics specially from isms

these are most important topics to be prepared well for better marks according to best of my knowledge.
Logic is base
ethics and other isms are extensions of philosophy
one should consult History of Muslim Philosophy both volumes for less chances of being faint during the paper so do consult History of Muslim Philosophy it will support u.....

Best of Luck....
Thanks to my Philosophy Teacher Brig.(R) Prof. Dr Ehsan ur Rehman who introduced philosophy to me n i found its so easy n people feel fear of it