How to find out if a company online is legitimate?

When exploring the legitimacy of an online company, especially in the realm of cryptocurrency and finance, it's crucial to take a meticulous approach. Could you elaborate on some of the key steps one should undertake to verify the authenticity of such a business? Is conducting a thorough background check, verifying regulatory compliance, and checking for any red flags or negative reviews among these crucial steps? Furthermore, how can potential customers ensure that their investments and personal information are secure when dealing with online companies?