Here’s a powerful tip for giving feedback after a performance. Before you say a word, ask the performer how they thought the performance went.
People can reflect on their own performance. In most cases, they do a good job of identifying what they did well and what they wish to improve. At least, they have hints of both these aspects that you can later build upon.
Having them go first gives you a foundation to layer your own feedback on top. On listening to their answer, you can cut out duplication and alter the level of your own feedback’s detail. More importantly, self-evaluation fosters trust. Since you have heard them out with an open mind, they are more open to hearing you out.
Effective feedback requires the giver to first find out where the recipient wishes to go, and help them get there.