Having never made a highlight successful i tend to shy away. But i suppose thats all part of the learning curve.
Im painting a Baneblade at the mo so will try and be a little more technical with it...
Mr. Simpson... Dead animals are on their way! LOL
Good clean job so far. You could try brass lines on the edges of the tin bitz parts. also washes of black and brown inks would bring the metal parts more to life. And dead animals stuck to the tracks;)