Preserve the original export
Keep one unchanged copy in an access-controlled folder. Work from a separate copy so you can compare any transformed values with the source. Use an explicit import workflow in your spreadsheet or CRM instead of relying on automatic type detection. Treat phone numbers, ZIP codes, record identifiers and order numbers as text rather than quantities.
Test fields that commonly change
Check a ZIP code that starts with zero, a phone field containing punctuation and any blank values. Confirm that the destination did not remove a leading zero, convert an identifier into scientific notation or shift a column because a name contains a comma. Review the date format and time zone separately; changing how a date looks does not change what that timestamp means.
Try a small import first
Map each source column to the intended destination field. Import a small sample into a controlled list and inspect the resulting records. Confirm the original order reference survived. If the destination automatically starts outreach on import, disable that action during preparation and follow your approved review process before activating any contact workflow.
Reconcile accepted and rejected rows
Record the count submitted, accepted, skipped and rejected. Read the rejection report before rerunning the file. A second upload of the entire batch may create duplicates if the destination does not match existing records reliably. Correct the rejected rows and use a stable record identifier where supported. Keep import logs with the original export for later troubleshooting.