The fastest way to lose trust in a WAF is to switch a policy to blocking on a Friday and take out a legitimate customer journey on Monday. It is avoidable. A policy earns the right to block; it does not start there.
Start transparent, and mean it
Run the policy in transparent mode long enough to see a full business cycle, including month-end and any batch jobs. What you are buying is a picture of normal, so that abnormal actually stands out later.
Stage signatures before you enforce them
New and updated signatures go into staging first. Staging logs what a signature would have done without acting on it, which is exactly what you want before trusting it against live traffic.
- Keep signatures in staging for a defined period, not indefinitely
- Review what each staged signature matched before enforcing it
- Enforce in batches, then watch, rather than all at once
A false positive in blocking mode is an outage with your name on it. Treat every one as a production incident waiting to happen.
Triage learning suggestions like a queue
Learning suggestions are not a to-accept-all list. Read each one, decide whether it describes legitimate traffic or an attack pattern, and only then accept or ignore it. This is the slow, unglamorous work that makes the difference between a WAF that protects and a WAF that everyone quietly bypasses.