Be honest and thorough with your feedback, give examples and fully clarify why you're having the conversation.

The more clarity you can provide, the better the critique will be received.

This is not a conversation you want to have in the spur of the moment.

Think of what you’re going to say, and prepare for the other person’s reactions. Being prepared you are more likely to stay even-tempered, thus delivering a more solid critique.

The words you use during the conversation matter. Outline the critique and the reason you’re having the conversation.

Also, talk about the outcome you’d like to see. Illustrating a positive outcome gives the other an aim to work towards, and helps them understand why they’re being called out.

Clearly explain the reason for the conversation, the specific critique, and then offer suggestions to improve.

Even if the conversation is to fire an employee, you should still offer a suggestion that will help them improve in their next job.

Talk in an even tone and keep it professional. Don’t let your emotions dictate your delivery or the other will too. This is especially important when talking to someone you are closely with.

Try to focus at things solely from a fact based standpoint. When emotions start to take over, remind yourself that the more in control you are of your emotions, the better you'll be able to deliver the message.

Be stoic in your delivery but empathize. Think of how others will feel during the conversation, and allow them to process their emotions.

Give them time to collect themselves and explain the reason for the conversation to help them understand. If they're really taking the news poorly, remind them that you’re delivering this critique to make them better, and you want to see them succeed.

Through questions others can better process what’s happened, and it allows you to clarify and solidify details of the conversation. 

If you aren't sure that the other person fully comprehended the conversation, ask clarifying questions to check their understanding.