Dear rehan it is a fact that i am going to appear in 2012 or 2013 by one should prepare himself according to the time.i have ample time for it that's why i asked for a strategy to prepare it excellently till my css exam.for the optional sub my father is the most suitbale guidline to me as my father topped the sibi division in pcs in 1991,but my father is not a science professor.he is educationist.