Start by defining users, resources, permissions, primary workflows, and failure states before writing components. A production application should have explicit requirements for loading, empty, error, and permission-denied states.

Write the main user journeys as a sequence of screens and actions. This prevents architecture from becoming a collection of components without a coherent product model.

Split the capstone into feature boundaries and shared primitives. Identify server state, client state, URL state, and ephemeral component state separately.

Define public APIs between features. Decide which data-fetching mechanism owns caching and invalidation. Establish an error boundary strategy before implementing individual pages.

Build one complete vertical slice first: route → UI → form → API → loading/error/success → tests. Once the pattern is stable, expand to additional features.

Avoid creating dozens of generic abstractions before you have repeated use cases. Let duplication reveal the correct abstraction boundary.

After the application works, profile realistic workflows. Measure initial load, route navigation, large lists, typing into expensive screens, and mutation feedback.

Optimize only the measured bottlenecks. Typical improvements include route-level code splitting, reducing state propagation, memoizing expensive calculations, virtualizing large lists, and eliminating request waterfalls.

Before release, verify keyboard navigation, screen-reader labels, responsive layouts, loading states, error recovery, authorization, network failures, empty data, slow devices, and browser console errors.

Run the full test suite and production build. Verify source maps and error reporting are configured appropriately without exposing secrets.