How do you know if a website is reliable or unreliable?

Good day, I have a question regarding the authenticity of websites in the realm of cryptocurrency and finance. Could you please elaborate on the key factors one should consider when determining if a website is reliable or unreliable? Are there specific red flags to look out for, or is there a standardized approach to vetting the credibility of these platforms? Your insights would be invaluable in navigating the complex landscape of online financial transactions.