Start with place, time and jurisdiction
Identify the state, county and town for each event because most vital, court and land records were created locally, while censuses, immigration and military files may be federal. County boundaries changed frequently. Build a timeline of jurisdictions so a missing record is not searched under the wrong county or state.
Follow the strongest record sequence
Move between federal censuses, state censuses where available, vital registrations, church records, probate and land. Passenger lists and naturalisation files may connect an immigrant to an earlier home; military service and pension files can add relatives and testimony. Newspapers can confirm communities, deaths and social context.
Preserve evidence and local context
Cite the record creator, jurisdiction, collection, enumeration or file details, page or image and repository. A database index is a finding aid; verify the image or original record. Compare ages, neighbours, occupations and migration patterns before merging people with common names across states or generations.