Do no reprove him in such a way that you bring sin upon yourself, such as by shaming him through reproving him in public.
A. S. HARTOM
The most challenging and important communication skill is the ability to let people know when you are unhappy with something they have done. Letting them know about your discontent in a way that focuses on the problem, not the person, will lead to trust, understanding, and mutual respect. This important skill can be used at work, but it is important to do this in your home life too. Here's the secret to doing it well:
Do it in private. Allowing other people to see and hear the discussion will exacerbate the problem and involve more people than are needed.
Get an invitation. Ask the person when it is convenient to meet. This will get buy-in to the process. In the unlikely event that the employee refuses, you will need to be more assertive. Agree to a venue. The feedback should be obtained as soon after the problem occurs as possible.
Be specific. Tell the employee exactly what you know without diluting your thoughts into generalities. If possible, give numbers, dates, and places. Avoid using the words such as "always" or "never." It is not necessary to exaggerate in order to make your point.
Be assertive. Work hard to satisfy your own needs. Being assertive means:
Using the "I" word, never the "you" word. Saying "I have a problem and need your help" will garner greater support than "You are doing this or that."
Speaking with a firm, deliberate voice.
Maintaining eye contact.
Projecting confidence in your posture.
Choose your words carefully. Don't use inflammatory language or the person will focus on the way feedback is being given rather than on the message.
Involve the person in finding a satisfactory solution. Ask how he can help. Don't tell him how to solve the problem, as this will reduce the buy-in necessary to have the issue resolved.
Summarize your understanding with agreements. You could say, "So what I'm hearing you say is - . Is that correct?"
Summarize the discussion at the end so that you both clearly understand what was said and what was agreed upon.
Acknowledge the person afterwards when her behaviour is in accordance with your agreement.