Define the question before collecting
Write down what you need to establish and what evidence would be sufficient. Finding the source of your own photograph is a bounded question. Compiling every available detail about a stranger is a different and more intrusive activity.
Respect access boundaries
Use information that is legitimately available to you. Do not bypass private accounts, impersonate someone to gain access or seek leaked credentials. Public availability does not make every reuse appropriate.
Separate observation from inference
“This page displays this image” is an observation. “This person controls this account” is an inference that requires other evidence. Log the source, date and uncertainty separately so one tentative association does not become a chain of supposed facts.
Stop when the purpose is met
Avoid retaining unrelated details or publishing private contact information. For high-stakes decisions, use an appropriate formal process and qualified guidance. Start with the people-search overview and background-check distinction.