We most easily perceive the qualities of a material and the shape it is formed into by how it contrasts with other materials and shapes.
When seeking to highlight these contrasts, consider color.
Select materials that have different colors to help highlight the differences between them. Consider materials that naturally have contrasting colors. Also consider coloring or painting different materials and details different colors to help highlight the contrasts between them.
In the example pictured here, sheet metal and concrete are used together on the exterior of a building. Uncolored, the concrete would have been similar in color to the sheet metal. The result would have been a bland blending together of the materials. By coloring the concrete, the architects have brought attention to the contrasting materials. This in turn invites you closer to appreciate the other differences in the materials such as their texture and reflectivity.
The same principle can be used to bring attention to the contrasts between different details. It can be very effective to color large areas such as walls or ceilings a single neutral color, and make smaller pieces like trimwork a shade darker and stronger.