Start with a source you can trace
Record where an observation came from, when it was captured and what use is permitted. Public availability is not a substitute for a documented publication decision.
Make the comparison fair
Preserve the amount, currencies, origin, destination, funding method and payout method. Keep an indicative reference rate separate from the price of a specific transaction.
Make uncertainty visible
Unknown fees and incomplete conditions should be visible, not hidden inside an apparently precise total. Older observations should be identified as historical rather than presented as a fresh quote.
Review before you publish
Check the source, permission, validity and context. A country on a research map is not evidence of a live feed. Publication should explain the limitations that could change a reader’s interpretation.