Start with the address
Read the complete domain rather than relying on a logo or page title. If a message claims to come from a service you already use, open that service through a known bookmark or address instead of following an unexpected link.
Check the context
Consider how you arrived at the page and what it wants you to do. An urgent request for payment, a recovery phrase or an account code deserves a pause. A polished design and an encrypted connection do not, by themselves, establish who operates a site.
Keep the decision reversible
When you cannot establish the source, avoid submitting sensitive information. Contact the organization through a separately verified channel. Keep the URL and message context if you need to report the incident.