Paint colors

Hello all,
I just started assembling one of four Roundhouse C&NW passenger cars. The sides are nicely done but everything else is styrene black. I have painted the handrails bright yellow. What are some colors for the rest of the cars? Like the air tanks, tool boxes, steps, brake wheel etc.
Thanks in advance,
Bruce in the Peg (only 20 below today)

Bruce,

What types of cars are these?

Streamlined? Heavyweight? Old West?

Antonio, they are streamlined circa 1950