In the workplace, handling the mistakes of a fellow worker requires a delicate touch. You need to deliver your message strongly enough, so your help is heard and understood, but subtly enough so it doesn't undermine operations or create resentment. The secret is to present yourself as a friend, someone who has been through the situation before and can help. Outline the nature of the mistake and why it causes others problems but affirm your confidence in your coworker's abilities. If your comments are received favorably, suggest ways to correct the mistakes, then offer to be available for questions and help. If your peer disagrees with your perception, or gets angry, remain calm, but restate your prior comments, and how the mistakes interfere with efficiency. They must be made to understand that either they correct their mistakes, or you'll go over their head.
This script can be modified to: