Identify the actual gap
Write the missing link as a question. Missing a birth record is different from having no evidence of parentage: other records may address the relationship.
Revisit assumptions
A surname may have changed, a boundary may have moved, or an age may have been reported incorrectly. Recheck the original image when available, rather than relying only on an index.
Look beyond the individual
Siblings, witnesses, neighbors, and associates can provide context. Compare their movements and relationships without assuming proximity proves kinship.
Know when to pause
Some answers remain inaccessible or were never recorded. Document what you searched and why a candidate does or does not fit. Future access or new evidence may change the conclusion.