Take following steps to realize your dreams:

-Go thru past paprers of CSS and familiarize yourself with the paper pattern.
-See which optional subjects suit your aptitude or appeal to your interest.
-Carefully choose your optional subjects.
-Buy the relevant books.
-Make notes on topics/questions from the past papers... for example for a specific question/topic consult atleast three different books/sources and then make your own notes on that question/topic. Follow the same strategy for all questions.
-Read Dawn Newspaper regularly, especially the editorial section and the columns.
-Practice writing on blank papers.
-Make a plan, set a goal and devise strategy to achieve them.
-Start with compulsory subjects first.
-When note making is done, ... revise revise and revise.

I hope you get the idea.

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"MAST TAUKALI ae DUA"