When giving people feedback a useful pattern is to make it:
Actionable: Can the person do something about this feedback. “You did a great job” might make someone feel good but there isn't very much they can do with that information.
Specific: Does it pinpoint a specific area. “I couldn't understand what you were saying” isn't as good as “it would have been easier for me to understand if you spoke slower”
Kind: Is it presented with the recipients best interest in mind in a way that invites a positive response. “Here is a list of 10 specific and actionable ways you can stop sucking” isn't the best way to give feedback.
This acronym can also be a good reminder that feedback often lands better if you ask someone before giving it.