OP OP her/also dude who was hemming and hawing last night:
I really appreciate everyone's support and advice. FWIW, I have gone to Career Services, I have done mock interviews, I have solicited advice from people who have rocked interviews, I have even talked to the last people who interviewed me for a job I got: the clerks from my j-internship. Some of it was helpful, but most to all of it was unneeded. The poster with the stickied note "The Mechanics of OCI blah blah" tells you everything you need to know. I kinda figured he was simplifying it, but nah, it's a real simple process I believe. I was over-selling, talking too much, being too specific, not being deferential enough, not asking the interviewer enough about themselves, instead asking tough and hyper-specific Qs about the firm: all nice tools to have in your arsenal for 1 in 10 interview that wants to go the conventional route or try out some behavioral techniques, but generally superfluous and harmful.
I hesitate to say this until I've got an offer in hand, but I think this is it, 100%:
1) be friendly, enthusiastic, make some (but not too much eye contact), don't fidget, paste a smile on your face, have good posture
2) let the interviewer control the interview (sometimes I would start asking questions too quickly, as soon as I saw an opening, and this was generally a mistake)
3) be ready to give a quick anecdote about any resume line that makes you (A) sound good (B) makes the experience sound at least somewhat useful and (C) makes the experience sound so unbelievably god-damned positive
4) be ready with concise answers to the questions you will almost invariably get, like "why law school" and "why X city" these can be amusing, cogent, subtly persuasive, whatever, but they need to be quick, semi-coherent, and have a really positive spin.
5) your "why firm Y" answer needs to be enthusiastic and show some very basic familiarity with the firm, but should be concise and should not go into too much depth. take these admonitions even more seriously when talking to an associate. also, focus not so much on what vault, etc. says but how their website talks about the firm's strengths. this is how they like to perceive themselves.
6) somewhere, somehow, work in a non-law (and probably non-work) related experience somewhere. a hobby, etc.
7) refer to (2) and make sure the question asking phase has begun before you start asking questions.
8. ask the interviewer about themselves and their experiences. especially associates. act so fucking impressed oh my god by how much responsibility they've taken on so quickly. with partners, be impressed by their knowledge of the firm and their insight into the firm's strategies and practices. I mean, be really fucking impressed, even though they will likely be a total asshat.
9) ask questions that show you've done basic research ("now, your summer program allows you to get a variety of experiences. [partner]: how are those assignments given? [associate]: what sort of assignments did you do during your summer?")