For the rails I used flat black then over sprayed the black with a rustoleum rust color. For ballast,,,, HO ballast is perfect. The rock size is, scale size, so that a 1/48 person could pick up a rock with their hand and throw it. Just as you can with real ballast. the rails were removed from the ties then painted and I sprayed the ties separately with gray paint, then apllied a black wash over the gray. I score the ties with a razor saw before painting.
The ballast doesn't over power the track or the trains.
Best of luck to your project.
