Effective preparation has three phases: map the evidence, test the floor, fix what matters.
Most organisations treat the certification audit as an exam. The result is a heavy push a few weeks before the visit, then an immediate relapse. This approach is costly and does not improve the system in a lasting way.
The first step is mapping the evidence expected for each process. Every requirement must link to an existing, dated and accessible record. Gaps then appear clearly, before the auditor arrives.
The second step is a floor test: question operators the way an auditor would, without traps, to measure the gap between the written procedure and real practice.
The third step is prioritisation. Not all observations carry the same weight: start with product safety, traceability and change control.