What helped me:
1. Close your eyes and take a deep breath before and after your MMI sessions, each session is a blank slate, and one session doesn't carry over to the next. You can mess up on one and not affect the others down the line.
2. Know your application inside and out and try to base your answers off of it as much as possible (matching your experiences to answer the prompt is a clear-cut bonus). They document the highlights of your answer, so you must align your answers to your application. Also, note that some MMI's may come from left field (not specifically from UICOM but other schools. UICOM does a great job of keeping things pretty standard). I would practice some beforehand so that you're calm and ready when these types of questions arise—There are tons of references/ documents online with such MMI questions. PRACTICE, PRACTICE, PRACTICE, PRACTICE. Try to conduct MMIs with faculty, physicians, family members, or non-science individuals who may have the time to sit down and discuss different MMI scenarios. English/Writing/political science professors seem to enjoy MMIs.
3. Try to repeat the prompt to show that you have an understanding of the prompt and you understand the who and what (the players and the situation)
4. For MMIs, you cannot be wrong- If you are for abortions, cool. If you are against abortions, cool. Make sure you define your perspective and consider others who may not share the same values or opinions. (They may be testing you for cultural relativity and open-mindedness, which are essential, especially how diverse our society is becoming). Always think medicine needs to have individuals with different perspectives to make it better. If we can't express our views or are somehow limited from speaking about different cultural experiences, how can medicine evolve?
5. If you can, try to abide by the four tenants of ethics (Beneficence, Non-maleficence, Autonomy, and Justice). These will be your guideline as your answer prompts that may be controversial (Abortions, Universal vs. Single-payer healthcare, child abuse, advance directives, physician-assisted suicide, etc.) All physicians and healthcare professionals SHOULD abide by these tenants, no matter religious, cultural, sexual, ethnic, or political background.
Cheers and all the best!