What are some of your company's best practices for an internal audit?

One thing that is not done nearly enough is to teach employees what to expect from an audit, and for the auditors, instructions regarding how they should "behave respectfully" during an audit. I wrote a blog around how each party would do well to put themselves in the other party's shoes, "Relationship Building with Auditors: It is Well Worth Your Time"
(https://www.proformative.com/blogs/ernie-humphrey/2015/01/17/relationship-building-auditors-it-well-worth-your-time)
Both parties need to be ready for any audit, and the expectations should be clear in terms of how long it will take and the objective of any audit.