I don't remember where I heard this, but the method was described to me using the story of how a suspension bridge is built: first an arrow with twine tied to it is shot from one side of the canyon to the other. Then that twine is used to pull thicker twine, then rope, then steel cables, and so on. From a string to a suspension bridge, with the gap between the canyons conquered the entire time. To achieve large scale software projects, start with the thinnest logical twine that goes from start to finish for the project at hand, and build out with a start to finish operating environment as soon as possible and throughout the duration of the project.