Hey Oppo: Serious Question Here About The Police

No, not the band. But, let's say I get pulled over for speeding. What do I do here? Then the cops want to search my vehicle. What are my rights? What do I do? If I talk to police I get one answer but reading online gives me another. I haven't been stopped yet (knock on wood) but it's bound to happen and I don't want to seem to up front or too hidden. HELP PLEASE!