Hi Mike,
I make models of buildings and try hard to make them photo realistic within the constraints of GE. I always start with a large number of photos of the building. This gives you an idea of shape and proportion as well as the textures to paste onto the surfaces of the model. I use PaintShopPro; Photoshop is probably better or easier. The important thing is to manipulate the photos so that they fit properly on the model's surfaces. Little details are important for realism. Also, I find that using colors from the Materials menu don't look real: they're too even and smooth. Real objects have flaws and mixed colors.
There are some good tutorials on the SU web site that deal with this stuff.
Hope this helps a bit.
Tom