Start with the printed details
Write down the game or sport, card name, set name or set symbol, and collector number exactly as printed. Look at the back as well as the front. Keep any letters, slash or suffix in the number. Do not replace those details with a listing title.
Match the printing, not just the picture
Record the language and finish, then look for edition marks, promotional stamps or other variants. The same name and artwork can appear on different cards. If the finish is hard to see, ask for a clear image at an angle rather than calling it foil from a single glare spot.
Check an official publisher card database or checklist where one exists. For Pokémon, the official card database offers name and advanced search. Compare the card number and set as well as the image. For another game, use that publisher's own reference where available.
Keep identification separate from authentication
A matching database entry helps you identify which card an item is meant to be. It does not prove that the physical copy is authentic. Unclear printing, inconsistent details or missing photographs are reasons to seek better evidence before buying, not reasons to invent an explanation.
For a graded card, record the grading company, grade, certification number and any qualifier. Check the certification on the grader's official site and compare its details with the item being offered. A certification lookup alone is not a guarantee that a photographed holder or card is genuine.
Build a reusable search phrase
Use this order: card name + set + collector number + language + finish or variant. Add “raw” when researching ungraded copies, or the grading company and grade for a graded copy. Search results still need checking individually; extra keywords do not make every match comparable.
Your stopping rule
Move on when you can describe the exact version without relying on the seller's headline. If the number, language or finish remains unclear, keep that field as unknown and ask a focused question. Resolving identity comes before comparing price.