Number of Colours In a Building's Facade

We all like good renders of buildings, both externally or interior works. The question we need to ask ourselves are as follows;

1. How many colours much a person use?
2. Which colours are suitable for external works and which for internal works.
3. The quality of the materials used to finish the surface.
4. How appealing is it to the client's eyes and people who might be interested.

Presentation of work is more crucial than filling all the rainbow colours on a building, for me, I prefer a blocked out background with vegetation, just to allow the viewers to focus on the subject building without being distracted.

Let us all learn from one another how to best sell our works out there.