After collecting a good amount of photographed reference material, I go to work on making them into usable textures. If correct lighting & perspectives are going to be used, then it should just be a case of tweaking them into position. These photos need to be taken on overcast days to avoid shadows or obvious light sources.
The photo reference is taken with a 10MegaPixel camera at a resolution of 3888x2592, these are then scaled & cropped down to 2048x2048. In Photoshop I use the distort tool to push them into shape, laying down a grid can ensure your lines are parallel to each other.
The buildings start as single polygon planes, which are UV mapped & have the final texture already applied, I slowly make cut's & extrusions following the underlying texture as a guide. A recent feature in 3dsmax is the 'Preserve UV's' option, when checking this you can easily move points & edges around without affecting the underlying UV's. Because the mesh is under constant change at this stage, it may require some remapping (the preserve UV's feature wont work all the time) wherever possible I use planar projections. For the sides of the extruded windows, I have given a generic Unwrap UVW & placed on the UV template to take best advantage of the texture. Any extrusions & bevels will quickly destroy the UV mapping.
Use the texture as a background in the UV editor to get even better control in matching your model to the texture.
Many smaller props are made to fill out the scene, it's the small details like these that make a scene interesting to look at. You might not notice them when first viewing the full image, but you would notice if they weren't there. I also make use of assets I've modeled in the past.