For managers, giving appropriate and effective criticism is a crucial part of the job. Done right, criticism can improve employee performance, increase mutual respect, and facilitate mutual goals. Done poorly, though, criticism can decrease employee morale and negatively affect the relationship. Emma Seppala, Science Director of Stanford University’s Center for Compassion and Altruism Research and Education, and Deborah Bright, Author of The Truth Doesn’t Have to Hurt, have identified four key ways to ensure constructive criticism:

1. Engage the employee in problem-solving. Instead of giving criticism in general terms and leaving the receiver to guess how to do it right, you can engage the employee in a problem-solving process and come up with an implementable solution. This communicates that you are actively trying to help them improve, and communicates respect for the employee by engaging them creating a solution.
2. Connect it to what matters to the employee. You can make your criticism more effective by connecting it to what is most important to them. If you know that the employee cares about the respect of their colleagues, for example, connect the issue to how their colleagues might perceive them. If employees see this link, they will be more receptive to criticism and more motivated to work towards a solution.
3. Learn individual preferences. People have different preferences for how they like to receive feedback, so ask them early on in your relationship. Do they prefer email or in-person? Do they prefer feedback immediately after each performance, or do they prefer it to come collectively? If you heed their preferences, you can increase the chances of it being effective.
4. Pay attention to body language. Convey trust and openness in your body language to increase receptiveness:
   1. Make eye contact to show them you are fully present.
   2. Keep an open posture (don’t cross your arms or legs) to convey responsiveness.
   3. Keep your voice and facial expression neutral to communicate that this is professional, not personal feedback.
   4. Pay attention to your breath: shallow breaths communicate stress or anger, and sighs communicate annoyance. Try taking some deep, even breaths to make your employee feel more comfortable, so they can pay attention to what you are saying rather than what you might be feeling.

Source, Source