Cleaning Supplies
Being this is kinda right up my Alley, Since I did this Sorta thing at the Local Garage through my High School years and a few years there after.
On some things that are Tarnished due to Whatever Reason (Brake Dust, Exhaust soot, or just Sitting around) I've found on Some Certain types of Chrome Trim, Ultra Fine Steel Wool (like Grade #0000) Can Polish things right up, Although I will also Say that I've seen that same type of Steel Wool Do damage too, so I wouldn't Suggest it on all Aplications and Forms of Chrome Trim
Personally, I Stumbled Across a Product made by Eagle One Cleaning Supplies that I gotta admitt, I like, Even though some of there products leave a little to be desired, I Have found that "Eagle One Original Never Dull Wadding Polish" (Or as I call it Mouse Nest in a Can, as when you open the can thats what it sorta looks like) Works Great.
The Times I've used it, It's Polished Dull Metal Finish's Right Up!
And it doesn't Leave a Wax type Build up in the Small little Crevices like Some Products do.
Car Soap On the Other Hand Is kind've a Tuffy.........As that Varries, from brand to brand.
On my Personal Vehicles, I Use a Product Called "Cherry Bomb" which is made by the "Car Brite" Brand, And I've never Ran into any Problems with it, as Far as Staining or Damaging the Finish of the Car.