Thank you for this input - very helpful. Other than understanding the site and why we are interested in it / communicating fit, what other things can we do to help us move up the list? And also - what are some of the red flags that generally could lead to someone getting moved down the list?
This is probably pretty vague, but to answer the question about moving up on the rank list: The applicants that I get excited about are the ones that are excited about my program. If you are genuinely interested in a program, I think communicating that interest is important (without obviously breaking the rule of saying where you plan to rank the site). Being prepared and knowing the site well is a "turn on." Asking good questions that are site-specific can also communicate you are familiar and interested (i.e., I see on rotation X there is the possibility of supervising practicum students; what might that look like? Rather than just asking if there are opportunities to supervise). Giving examples from your own experience to highlight your responses can also be helpful.
The other question from multiple folks was about red flags. Most are really blatant that even other applicants the day of will notice, such as narcissism, seeming competitive with other applicants, seeming argumentative, "knowing better" than others, etc. There have even been applicants who have argued with their potential supervisor during the interview. I understand if you don't agree with what your interviewer is saying, but there's no need to hash it out in an interview (and the arguments were very trivial). Not asking any questions can be a red flag. I know many sites allow ample opportunity to ask questions, but even with your last interviewer, it can't hurt to ask the same question just to get a different perspective. Also, make sure you interact with the current interns, if given the opportunity. We've had candidates that are shy and aren't as open to asking questions, but making eye contact, nodding, etc. can go a long way to show you're engaged (although definitely take advantage of the time you have with them - it can help with your own decision making). We've had interns tell us that there were applicants who were on their phone the whole time and didn't talk to them at all. I know you may need to check your phone - especially if you're still waiting to hear from sites, but if you want to check your phone, do it on a break in the bathroom.
Someone else asked about nervousness. It's completely normal to be nervous on an interview day, and I hope that most will recognize this (we're psychologists after all). Heck, I'm always a little nervous because I want the applicants to like me/the site too! I think it could be detrimental if you're so anxious that it is impacting how you respond. For example, if you're giving one-word answers, completely having lots of mind-blanking moments, you could also look disinterested or not prepared. If you know you get very anxious for interviews and may have these sorts of problems, then ask your faculty to do some practice interviews. Or do some with your classmates. Or stand in front of a mirror.
Although this question wasn't directed at me specifically, I wanted to give my input re: facial piercings and tattoos. I have no problems with these, but I do know of other faculty who have brought it up in ranking meetings. The concern is usually questioning the judgment of the applicant since many are told to remove them or cover them for interviews. Some places also have dress codes against these things and I wouldn't expect an applicant to know the ins and outs of the site's dress code, but it could give pause from other faculty. I would say, if you want to be cautious and not jeopardize your chances, remove them/cover them for your interview. It's possible that one person (who you may never even work with) may have a problem with it and it could affect where you fall on the rank list. On the other hand, if you didn't want to match at a site that had judgments about it (even if it was your absolute top choice), then wear them.
TLDR:
Be genuine, be prepared, be interested in the site. It's fine if you're nervous. Remove/cover facial piercings/tattoos if you want to be conservative/not want it to affect you (you would be okay not matching at your top site for that reason).