In addition to the audit process and schedule, the requirements for both auditors and lead auditors should be defined.
Years of Experience
These requirements are usually defined as a number of years of experience with auditing as a function, external audit certificates (ISO offers a lead auditor course) or a minimum number of hours of training.
Qualified Auditors
It is best practice to maintain a list of qualified approved auditors and lead auditors.
There are many audit formats, such as a turtle diagrams and checklists.
Turtle Diagrams
A turtle diagram starts with defining the process, and then listing the inputs to the process (typically on the left), including equipment, procedures, and support processes and then listing outputs on the right (performance indicators).
The final diagram resembles a turtle with the process being the shell inputs the head and outputs the tail with legs being the other fields mentioned.