noise under car

The type of noise could give you a clue. A squeek normally is the result of worn bushings. A rattle may indicate loose suspension parts of a loose mounting bolt on exhaust system. Klinks resulting when brakes are applied or while turning could indicate a worn stableizer bar link. Also a brake problem. Try to notice when the noise occurs. When striking a bump, turning, braking, backing, etc. It's possible to rule out things depending on when they occur.