After a coat of sanding sealer, the colours I chose for the wagon all came from the Humbrol acrylic range - 69 Gloss Yellow for the body, 33 Matt black for the chassis and RC414 Executive dark grey for the roof. All chosen because they were in a box of paint I bought second hand - I knew it would come in useful!
The lettering is a vinyl sticker. You press the front to fix the lettering to the clear carrier film, then peel away the white backing sheet. Place the film over the wagon side, where it's the perfect size so no lining up, run the letters down and then peel away the clear sheet.
This didn't quite work on the first sheet. The letters stayed on the backing, and I ended up peeling them away with tweezers, putting them on the wagon side and lining up by eye. The letters are pretty robust and with a little care, everything worked out OK.
The instructions say you don't need to seal them with varnish, but I shot some satin over the sides anyway.