Ethics of dating
Since a code of ethics can vary greatly depending on the corporate culture and a business' focus, the best place to start is by having a feel for what might go into your written guidelines.
Since a code of ethics doesn't actually create a product or service, it's important to remember that measuring its success can be somewhat subjective.
Philosophically speaking, ethics becomes a study of principles and how those principles affect personal and professional conduct.
From the framework of your business, it's important to develop a foundation of values and principles that guides your operations.
Constructive criticism is an ethical approach, as is providing support for future improvement.
Your sample code of ethics needs to include elements to measure and assess performance against the code, and include continuous improvement parameters. I would like to use this page (giving full credit) to teach my students how to write good business value statements for the HR Strategic Plan they are required to prepare.