I tend to always use Steam Era VR Wagon Red when painting Victorian rolling stock. This may be weathered with various colours to give the faded variations in colours, but it is always what I start with. There are some exceptions with some wagons being painted yellow, and here I also use the Steam Era colour to suit.
The passenger stock is typically VR Passenger Car Red which also has a Steam Era Models colour to suit although you can also use a Floquil Caboose Red. The passenger stock at various stages had either a black or a buff roof. For the black I use Floquil Grimy Black and for the buff either Floquil Mud or Humbrol 83.
For the more modern era of V/Line use Steam Era V/Line Orange Enamel (P6) for the orange and for the grey use Steam Era V/Line Grey Enamel (P5).