Map assets, entry points, trust boundaries, and likely threats before choosing security controls.
The core idea
Threat modelling is a structured way to ask what can go wrong and which protections matter most. It starts with the application and its data, not with buying a tool or adding a long checklist.
A practical way to approach it
Draw the user, browser, API, database, and third-party services. Identify sensitive assets, trust boundaries, and actions an attacker might attempt. Prioritize mitigations by likelihood and impact, then revisit the model when architecture changes.
Try it in a small project
For a blog editor, consider account takeover, unauthorized publishing, malicious input, leaked API tokens, and denial of service. Map a concrete control to each meaningful threat.
Common mistakes to avoid
Threat models are not one-time paperwork. Keep them proportional, validate controls with tests, and include abuse cases as well as accidental failures.
Key takeaway
Keep the first version small, make your assumptions explicit, and verify the result with a repeatable test. For production use, check the current official documentation for the tools and versions you choose.