There are 5 most common sources for current affairs
1- News paper (DAWN news, Newyork times of express tribune)
2- Jahangir World Times magazine
3- Recent articles at PACE website
4- Random contemporary affair journals(online)
5- magazines like current affairs and Herald
Now what you have to do is keep reading/consulting these resources throughout the year and whenever you find something interesting which can play a role in CSS, cut it out from the paper and save it in a separate folder while highlighting the important facts and figues out of it.
Second step comes on 15th December. Get that folder (in which you have been saving all that data) and divide those cuttings as per their field i.e. education , health, security, policies, world conflicts, organizations etc
Third step is make a folder of blank pages for each category.
Fourth step is start reading those folders one by one and keep writing the underlined facts and figures in your folder of blank pages in point form.
Fifth step is very simple gather all the data and revise it.
This is how you will gather facts and figures of whole past year and can use them anywhere in your examination. From Essay to current affairs to Pakistan affairs, islamiyat to optional subjects, it helps everywhere.