The base was covered with a mix of wall spackling compound, water and a bit of white glue for extra strenght. After it dried, I gave it a black undercoat with Tamiya XF-1.
Tamiya's Desert Yellow, White and Black were used for the earth tones:
The road got a few veils of well diluted Tamiya German Grey and, after that, I covered everything with Vallejo Gloss
Oils paints will be used next. This is more or less how it looks now, as the photos were taken with my mobile phone.