The most important thing about giving feedback is that it must be about behaviour rather than some essential characteristics of a person, like “you are unfocused.”
You cannot sugarcoat feedback, or the spirit behind it and its importance can be missed. At the same time, you don’t want to make it a personal attack, either.
Give feedback on the action, not the person.
Radical honesty: The benefit of being radically honest: If you want to know what people are thinking, there is no substitute for simply asking them, preferably face to face.
If you want a culture of candor and accountability, you may want to consider simple, direct feedback, too.