Are you talking about rattles or road noise?
In case of road noise, have your alignment and camber checked to start with. Check your tires, tires with small square-ish tread are usually more silent.
If all that is well, your second step can be sound deadening. Use a dynamat sheet. You can start with the floor, especially under the gear console. Later you can move to the doors.
As for rattling, DIY is your best bet. No denter/Painter will drive the car with your ear and identify all squeaks and rattles the way you do.