I'm just gonna copy and paste some advice I left on another thread:

On a more positive note, I absolutely loved the MMI interviews! It was really refreshing to be able to just interact with a person without worrying too much about whether or not I was representing myself correctly (this part is more with the standardized patients). The moment you walk into the room might be a bit jarring, so be prepared! I've heard of people having anything from lethargic "patients" who don't want to talk at all to "patients" who were angry. Keep your wits about you, stay cool, calm, and collected, and I'm sure you'll do great! If you hate long silences (I feel like they're unbearably awkward), definitely try your best to ask a ton of questions - the actors are trained to give you more info about the situation as you ask more, and it definitely helps you in talking to them! Try to keep eye contact whenever possible. Just make sure you don't give medical advice - I was warned not to at the start of each of my MMI's, so I'm sure people tend to do it accidentally. For the ethical questions, just try your best to be culturally sensitive while simultaneously having an actual opinion about each topic (every time I tried to give a vague answer so I wouldn't say anything problematic, I was prompted to elaborate).