For Designers:
Before starting your game, consider having a quick conversation about what sort of feedback is desired. This helps keep the feedback portion organized and lets players know what to focus on.
Be respectful, courteous, and understanding when listening always. Feel free to clarify what you're looking for and have a conversation about feedback. But DON'T argue with playtesters. This doesn't help anyone!
If someone says something harmful during your session, don't hesitate to let the Event Host know so they can take action.
For Playtesters:
Don't be afraid to ask the designer questions or share any relevant information before or during the session! They want you to experience the game, and that means making sure you're comfortable to play.
When giving feedback, be honest but respectful. Feedback can involve harsh truths sometimes, however, this is not an opportunity to condescend the game or designer. Do your best to offer feedback that gives the designer opportunities to iterate and improve!
If you don't feel comfortable continuing or are unable to continue a game, don't!
Consider sharing parts of the game you liked to help guide the designer.
If someone says something harmful during your session, don't hesitate to let the Event Host know so they can take action.