First of all purchase any simple english grammar book. Do not read any writter at first, because you are new to CSS studies and can not digest any writter at this juncture; reading any writter would likely fed up you owing to advanced language and probably vanish your creativity. Therefore, in the beginning, must read daily dawn and any simple english grammar book. In the dawn newspaper, you need to start reading from the page letter to editor for 1 month.Do writting practice from the passages of dawn & get your write-up checked by ony senior or teacher. Learn the techniques of language. Dear you will see that with the passage of time you will develop your expansion of ideas to its other pages. As a matter of fact, the dawn is regarded bible for CSS. In the meanwhile, you may also start from Pakistan Affairs or EDS. Do not pay any attention to optional subjects for now, first get started with compulsory and then in the due course of time, opt "only scoring subjects". Good luck