Record the issue and outcome
A short description is more useful than keeping an invoice with no context.
Keep contractor information
Company name, date and invoice number can help with warranty or repeat service.
Track recurring failures
Repeated work on the same system may change a future repair-versus-replacement decision.
Protect account information
Service records can contain addresses, payment information or access details and should be stored appropriately.
General household information only. Follow product labels and manufacturer instructions. Electrical, gas, structural, hazardous-material and other safety-critical work belongs to appropriately qualified professionals.