What are some specific things which get you a higher interview score?
Others have kinda nailed but - it's really about personality and general fit. 5 years is a loooooong time and you want people who generally fit in with the overall vibe of a place. Being a normal human, easy to talk with, and able to discuss anything on your CV are the basics.
Honestly, the HR research shows overwhelmingly that we're all terrible interviewers, but we all think we're good at it. It's mostly a gut feeling thing and I'm not sure just how useful it is other than to weed out the weirdos. All the people on our rank list that fell below the match level all tended to match at really amazing programs - pretty much everyone else in the Top 10 as well. I don't know what would make someone be ranked to match at one top program and well below match range at another, but that's how it went sometimes. Even away rotators who were DNR'd for something seemingly terrible often went on to match well and I'd see them presenting at meetings and landing great fellowships.
I think we just aren't that good at selecting people, but since the applicant pool is already so good it's not as obvious how bad we are. We tried to get around this by asking everyone in the dept to interview and would even shut down all our clinics for a day to accomodate it. The hope was that with ~50 different people offering impressions, we might have a better shot at selecting the best candidates.
Rather than trying to get a higher score, I would view interviews more as you trying to figure out where you want to end up. It's a weird switch, but after your last interview when you sit down to make your rank list, you suddenly have all the power and all the responsibility and one switch of position may drammatically change your career. You'll want all the information you can get and you'll want to have a sense of who the people are and how you fit with them so you can make the best decision.
In this way, I think interviews in the match system may work pretty well as that vibing thing tends to be a two way street. People we really liked tended to really like us, and I think that holds true everywhere. As a result, people are more likely to wind up somewhere they fit well.