Judiciary Preparation

Can anyone tell me in detail how should I prepare for judiciary examination? What all subjects are there in judiciary? Which is the best coaching centre for Judiciary in Delhi NCR? Should I self study or go for coaching? Howmuch time should I invest in studying on daily basis to clear the examinations? Which are the best states that one should appear for? When does one become eligible to give the examination? What skills should I work on the most?

Thanks in advance!