Have your Alien Registration Card, passport, and entry or reentry permits with you for the interview plus any other documents indicated in your interview letter.
At no time should you LIE to the Bureau of Citizenship and Immigration Services. This is very important - no matter how worried you may be about something in your past. IF the BCIS grants you citizenship and then finds out you were untrue at any point - they can choose to revoke your citizenship and deport you.