When you have rendered wire from Edit UVW you can start texturing. I always start with a simple clear overall texture to prepare the base for further work. Using Total Textures I link diffuse and bump maps, then duplicate them to cover the whole area. It is important to work with diffuse and bump at the same time, on different layers, to make sure that diffuse fits to bump. In this phase I think of my model as a new object. Then I cover the main areas with duplicated textures and proceed to the next step.
I believe this is the most important and creative part of texturing. All the details create history of the objects; adding uniqueness and character to things. There are a lot of methods of adding details and dirt to texture - I will describe some of them. One of them is using something like ambient occlusion as dirtmask. You can add a rendered layer, as I have described above, in multiply and change the opacity or invert colours and use it as a mask for other layers. It is easy and fast, but not a very detailed method. You can also use dirtmaps from 3DTotal Textures, for example from Volume 5. Another way is by painting dirt and other details "by hand", which is the hardest and most time consuming method. I prefer mixing all three, so I use rendered ambient occlusion pass and a lot of dirtmasks with some painting.
Adding bump and other channels (specular etc)
As I have mentioned, I create a base bump map simultaneously with diffuse. However, in many cases bump channel requires more work, especially when creating more complex textures with many masked "base textures", like bricks under old paint layer, dirt, etc. Generally, it is a good idea to recreate the same process for a bump map as for diffuse, but keep in mind that you are building with depth, so bricks should be darker than the paint above them, and the hole in the wall should be darker etc. It is not just doing the same layer order and mask as in diffuse channel, try to include as much information about the "bumpiness" of the object as possible. You do not have to copy all the information from the diffuse channel, just a little dirt, graffiti, etc. Things like that do not affect bumpiness. The same rules apply to other channels, like reflect, glossiness etc. Do not copy bump map or just de-saturate the diffuse channel, but try to make something realistic.
Ok, so enough of the theory, now let us see how it works in practice. These are a few examples of textures from the scene.
AO and wire.
Base texture: england003 from Total Textures: Volume 12.
Another base textures: white colour for top and italy007 from Total Textures: Volume 12 for bottom.