The first advice for preparing for CSS would be that, from today you should read Daily Dawn until your CSS papers are over.
Second advice is that if possible than read Monthly magazine Herald and Newsline.
These things will be helpful directly in following CSS papers;

1. Essay
2. Current Affair
3. Pakistan Affair
4. International Relations
5. Sociology

Reliable source of knowledge and creativity :

This is Second source of knowledge for preparing CSS.

The most reliable source for information and presenting of news in concise is broad castes by BBC URDU and BBC HINDI which has close effects particularly on Pakistan and India and generally upon Asia. So for having knowledge and command on Current affair people who are thinking to apply for CSS should start listening BBC URDU and BBC HINDI, particularly from 7 PM Pakistan time to 8:30.
With that they should keep visiting and reading the web site www.bbcurdu.com and particularly BAAT SEY BAAT of Wusatullah Khan, as his articles helps to have creativity, and nice way of analysing and with that it contains concise information on particular topic.