Use a password manager, SSO where possible, and role‑based access tied to revocable service accounts. Store secrets outside spreadsheets, restrict sharing, and set alerts on new connections. Quarterly key rotation and offboarding checklists close loopholes that attackers and former contractors often exploit.
Decide once how to label merchants, categories, taxes, and project codes, then enforce with validation. Deduplicate by transaction ID, not amount. When every line is tidy, dashboards tell the truth quickly, and downstream automations stop breaking under the weight of tiny, inconsistent differences.