Start with an anchor
Preserve the source copy before you clean.
The first step in a careful text-cleaning workflow is not a change. It is preservation. Keep a source copy before working on the text so that the original remains available for comparison. This gives the review a fixed point: you can look at what was present, what was changed, and what needs another pass.
Preservation also keeps the sequence honest. A cleaned version may look more orderly, but appearance alone does not show whether meaning has stayed intact. The source copy lets you compare quotations, citations, names, numbers, and terminology instead of relying on memory. Treat it as the reference for the rest of the workflow.
Keep the distinction clear: the source copy is the reference; the cleaned text is the version being reviewed.