All 3D software packages have a material structure made up of channels or layers. It means that there are channels for the different material components (diffusse color, bumping, reflection, refraction, glossiness, specularity, displacement and so on).

I usually work with a diffusse channel and a bump channel, and if the material requires, I use maps for glossiness and specularity. Reflection and refraction are used for specific materials, for example I used this in the windows glass panels.

I usually work with different material types, but in this kind of scene, the standard material fulfils almost all requests.

A very useful material is the multi-subobject mat, that lets you handle a lot of materials for a single object according to the material ID's that you assign to the different polys that conform the object.

In the image above you can see a multi-subobject material I used in the scene. The map navigator shows you the internal structure. The different materials are assigned to the building walls. Every channel has a UVW map assigned in the stack to project the map in the object surface.

The real secret in material design is to know how to combine different kinds of maps to achieve the goal we need.
A good trick I use, is to add more irregularity to a bitmap, mixing it with a procedural map. In the example on the right, I mixed a bitmap with a noise procedural to create a more uneven surface, in bumping channel.

In this scene, I mainly used common UVW projections, as planar, cylindrical and box, but in some specific cases a more detailed adjustment is needed. In this way, we use Unwrap mapping. Once the geometry is unfolded in a planar projection, you can paint it in an external program, and back in the 3D application, this map matches exactly the object geometry.
With only one bitmap image you map an entire object.

The scene was completed with similar materials, always using 3DTotal textures, sometimes mixed with some procedurals.

To render correctly in different third party renderers as Brazil or V-Ray, some specific materials have to be set up. Most of them are related to refractive or reflective materials, including raytracing features. So, V-Ray for example, offers us VRay Maps for reflection or refraction effects, VRay lights, VRay shadows, and so on. If we plan to render in this kind of engines, we'll need to set a special configuration for our scene.

Well, now we move to the next step: lighting and then, rendering. Let's go on buddies...