The question determines the method
Records, open sources, interviews, field observation, geospatial analysis, and aerial collection answer different kinds of questions. Method follows the information requirement.
Capability does not establish authority
A source or tool may be technically available while remaining inappropriate for a particular purpose, jurisdiction, client relationship, or expectation of privacy.
Use the least intrusive adequate method
Collection should be proportionate to the question and its consequences. Existing reliable records may resolve an issue that would otherwise consume field time or create unnecessary exposure.
Preserve the collection boundary
Document what was authorized, where collection occurred, which sources were used, what restrictions applied, and how the resulting material may be retained or released.
Reassess as information changes
New evidence may resolve a requirement, expose a different problem, or make a planned method unnecessary. Collection design should change with the intelligence picture.