Merge PDFs only after deciding the reading order

List the source files in their intended order and note page counts. Remove duplicate or unwanted pages first, then merge with PDF merge. If the result needs continuous numbering, add numbers only after the final order is set.

Open the exported PDF in another viewer and inspect each transition between source files. Check orientation, missing pages, searchable text, links, and any metadata that should not travel with the combined document. A successful merge notification does not prove the document reads correctly.

Keep the individual sources until the merged file is approved.