Congrats! The MPH interview was pretty conversational. I felt warmed up and ready to go after the MMI. Most of the questions were pretty standard and things you will expect. I would recommend reflecting on why you want to go for the MPH and how you see that affecting your career in the future. I'm not sure what your schedule will be like, but I had the MMI in the morning followed by the tour and then the MPH part, so I was pretty tired out by that interview. Be prepared for a long day and you should be fine!
As for the MMI, there should be lots of tips on this thread, but everyone recommended reviewing topics on this website:
https://depts.washington.edu/bioethx/topics/
This site also has tips for practicing the MMI and some sample questions:
http://multipleminiinterview.com/mmi-questions/
Honestly, I did not do a whole lot of MMI-specific prep and I felt fine. Just try to relax and consider the questions carefully. Best of luck
🙂