Introduction: The guidelines offered in this paper aim to amalgamate the literature on formative feedback into practical Do’s, Don’ts and Don’t Knows for individual clinical supervisors and for the institutions that support clinical learning. Methods: The authors built consensus by an iterative process. Do’s and Don’ts were proposed based on authors’ individual teaching experience and awareness of the literature, and the amalgamated set of guidelines were then refined by all authors and the evidence was summarized for each guideline. Don’t Knows were identified as being important questions to this international group of educators which if answered would change practice. The criteria for inclusion of evidence for these guidelines were not those of a systematic review, so indicators of strength of these recommendations were developed which combine the evidence with the authors’ consensus. Results: A set of 32 Do and Don’t guidelines with the important Don’t Knows was compiled along with a summary of the evidence for each. These are divided into guidelines for the individual clinical supervisor giving feedback to their trainee (recommendations about both the process and the content of feedback) and guidelines for the learning culture (what elements of learning culture support the exchange of meaningful feedback, and what elements constrain it?) Conclusion: Feedback is not easy to get right, but it is essential to learning in medicine, and there is a wealth of evidence supporting the Do’s and warning against the Don’ts. Further research into the critical Don’t Knows of feedback is required. A new definition is offered: Helpful feedback is a supportive conversation that clarifies the trainee’s awareness of their developing competencies, enhances their self-efficacy for making progress, challenges them to set objectives for improvement, and facilitates their development of strategies to enable that improvement to occur.