How to build a navy from scratch

Where should a country begin when building a navy from scratch in the early twentieth century?

Begin with infrastructure, use cruisers and destroyers to develop the yards, and wait to build submarines until pressure-hull welding is dependable.

The answer starts ashore: shipyards, workforce, supply chains, and maintenance capacity determine what kind of navy can be built and sustained. Cruisers would be the first major designs because they test a broad range of machinery, weapons, and shipbuilding skills without immediately attempting the largest hulls. Destroyers and other smaller combatants would follow as the industrial base gained experience. Submarines come later because a pressure hull demands exceptionally reliable welding and quality control. The sequence treats fleet construction as a learning system in which each class develops the skills required for the next.