These buildings become a classroom for us. Second, one should try to work along the lines of the architecture that is known. The most difficult square to choose in an area is often the first. Nothing is known about what might lay beneath the surface. Soon enough, things begin to turn up beneath the surface.
Architecture begins to appear.
Even the first square is an educated guess, informed by what you might have learned to expect. An important principle that often helps me make a decision in the field is to move from what I know to what I do not know. The things that we know in the field are simple things like walls and floors. It is like sailing along a coastline. As long as I see the Michigan dunes, I know I am not far from home.