Take your time
Weathering is a process and should be done with multiple layers. Blacks, dark greys, browns, white and silver scratches, matching the reference pictures as much as possible.
I used an airbrush which gave me much more control over the fade.
For the black splatters I took a toothbrush dipped in in watered down acrylic and just pushed my thumb through the bristles. Have a paper towel ready while doing any weathering to clean up if you go too far.