I have used a combination of steel wool and WD-40 for rusted splotches within paint... it worked for me. A brass brush on chrome parts work good as well. Diet soda and aluminum foil are more of a softer and cheaper approach but you can get just as good results with that combination as well

There is also Meguires scracth x which is sold at auto parts stores. Which is kind of good in restoring the brilliance of the paint. It removes some paint a little but it makes it shiny and squeaky clean.

I would just ripp off the decals.. it will probably look better without them.. unless your into labels