I would say study all about the Muslim society as a whole during the pre-partition era and struggle for Pakistan supplementing with the recommended readings by FPSC.

There is a cumbersome list of book recommended so which book are you going to follow??

Please seniors reply which books to follow...

There are very few books known to us for the existing facts and situation of the society, politics and economics as well the judicial, military and democratic institutions of Pakistan because before this re-shuffling, it was the history not the current issues which candidates prepared. I had read few books before preparation which were about the state of Pakistan not about history. Now that I have started preparation I feel those books were very useful. They cover the whole syllabus of Pak. Affairs, luckily for me.

Idea of Pakistan by Stephen Philip Cohen
PAKISTAN a hard country Anatol Lieven
A brief History of pakistan by James Wynbrandt
Atif Qureshi's brilliant book(I don't remember the name)

One can skip one or two of them if time doesn't allow. But Stephen Cohen's book is a must.
P.S: I have these books in soft but instead of being dependent on me, you can download them easily, they are available online.

U guys should prepare history from at least one best book
There is no need to get panic
One good text book is enough instead of 10 sub standard books