Asalam o Alikum

i have done b.arch. now i am planning to go for css in 2014
i am confused regarding my caliber....i don't know whether should i attempt it or not. if yes then please guide me.i have time and i am also hard working but the only thing which is pushing me back is..... i am confused that what kind of people and what kind of caliber is required for these competitive exams.