One of the main considerations for mindfulness in communication relates to emotions, because it's so easy to let intense emotions take over.
Good practice for mindful communication is to "red flag" any communications you're about to make if you are feeling intense emotions.
Give yourself space and time, if possible, to reflect and be sure whether the communication you're about to have is still in line with your best intentions and values. Is is fair? Are you about to speak in a way that you'd want someone to speak to you?