Attribution becomes useful when it helps decide where to spend the next pound, not when it produces the most complicated report.
Keep the chain intact
Capture source, campaign and landing page when the lead arrives. Store them on the contact and copy them to the opportunity. Connect the opportunity to the customer and payment record. If the identifiers disappear between systems, no dashboard can reconstruct the truth later.
Report commercial stages
Clicks and leads are diagnostics. The business decisions come from cost per qualified lead, cost per attended call, close rate, acquisition cost and collected revenue. Compare those measures by source and offer.
Accept uncertainty
Referrals, dark social, repeat visits and privacy controls make perfect attribution impossible. Use a consistent model, preserve self-reported source and inspect patterns rather than presenting estimates as certainty.
Review decisions, not vanity
A monthly review should end with an action: protect, increase, repair, test or stop. If the report cannot support one of those decisions, simplify it.
The goal is not to give every channel perfect credit. It is to connect demand to enough commercial evidence to allocate resources intelligently.