Carry

Valid call letter for your date and session (Mains: also the stamped Prelims call letter)
Original photo ID with the same name as on the call letter, plus a photocopy
Accepted IDs: PAN, Passport, permanent Driving Licence, Voter ID, bank passbook with photo
Also accepted: Gazetted Officer/People's Representative ID letter, college ID, Aadhaar/e-Aadhaar, employee ID, Bar Council ID
One extra photo, same as pasted on the call letter
Scribe form, if using a scribe

Do not bring

Print the admit card and check your name, photo, date, shift and centre address against your ID.
Keep the original photo ID named on the admit card, and a second one in case of a mismatch.
Find the centre on a map and plan to arrive well before the reporting time: gates close on time.
Read the instructions printed on your own admit card: they are the final word for your exam.