Start with the user workflow
List the actions users must complete, what data they need, what happens if the network is unavailable, and which tasks belong in an admin panel rather than the mobile app.
Design the backend early
Authentication, permissions, APIs, notifications, file storage and audit logs are not afterthoughts. They shape app reliability and the cost of adding features later.
Plan releases and support
Store policies, certificates, privacy disclosures, account deletion, testing, crash monitoring and version updates should be included in the release plan, not handled only after development is finished.