I'm not sure what your prep was like but the best advice I have is to practice a fair amount like it's the real thing with someone else. I found a couple MMI books online that I read through to help me develop an understanding of what a good response sounds like and I went through almost all of the practice interview questions with my wife who acted as the interviewer. So each question I would practice reading the prompt, walking in and shaking the interviewers hand, sitting down, and giving my answer while timed. After my time ran out, I would say thanks, shake her hand again, and walk out of the room for the next prompt. This is obviously different if it's a virtual interview but the point is to mimic the real thing as much as possible. I found it was really helpful for both learning how to work through difficult questions and how to not panic if I had a mind blank or made a mistake. During the real thing I did much better than my first practices and I left really happy with the experience.