How to Paint Buildings!

[Big Insect]

Very good tutorial - helpful and inspirational

One trick I was taught about weathering buildings - particularly in the age before concrete and tarmac roads is to go with 'splash up' zone.
When rain hits the ground around a building it naturally spatters mud up onto the build to a height of c 30-40 cm. Equally in a hot dusty climate you end up with dust kicked-up onto the building. So worth considering adding a weathering feature to your buildings as this helps them not look like they are a new build.

Similarly - unless you are a civilised (Roman or Chinese) ancient area - most buildings don't have gutters - rain is shed from the roof directly onto the ground - this also applies today to thatched buildings (I once lived in one and the rain drain off can seriously ruin flower beds or lawns). So you might want to consider a drainage line around building on the ground directly under the eaves where the water has turned the ground to mud. It's little effects like that which can hugely improve the realism of the final model.
NB: I have even used 2mm static grass in patches on a thatched roof to depict moss - particularly in the shadow behind a chimney or in a roof gully.

Cheers
Mark