Hi there, 

It's always best to reach out directly to the HR from your target office to discuss this question. 

Realistically speaking, the process changes often, and it can vary from role to role, so to make sure you have access to the best info, you should reach out to those who handle it. 

Best,
Cristian

First off, good luck in the interview!

Small note: To answer your question (which won't help you)…you can expect a case + fit interview but should also be prepared for market sizing. The difficulty will be the same as the London office. OW works in Automotive, Communications, Media, And Technology, Education, Energy And Natural Resources, Financial Services, Health And Life Sciences, Industrial Products, Private Equity And Principal Investors, Public Sector And Policy, Retail And Consumer Goods, and Transportation….so technically, any of these can appear. In New York, areas like Health and Life Sciences, Financial Services, etc. will be more likely.

1) But nothing I just said matters

Now, all that said, the #1 thing to remember for these interviews is that you should expect nothing.

These interviewers could give you all classic cases. Or, they could give you all completely unconventional cases.

Or, they could give you zero cases and just ask you brainstorming questions, scenario-based questions, expertise-based questions, etc. 

They might even create a case for you on the spot through scribbles they made on a piece of paper (yes, this just happened to one of my candidates).

Or, somewhere in between this.

So, train your skills, rather than studying like you do for a Biology exam in college.

Now, to your questions :)

2) what sorts of Cases to expect;

ANY and ALL. Please don't go in expecting anything. If you expect, it's more likely you will be wrong than right.

3) What mistakes to avoid,

Doing what everyone else does.

Don't go in expecting x and y. Don't go in with the mindset of “taking a test”. Go in with the mindset of being assessed as a consulting!

Oh, look here, just so happens I've written about the 4 most common mistakes to avoid :)

1. Waiting until you have an interview to prep
2. Using the wrong resources
3. Going cheap
4. Trying to boil the ocean

Here's some mindset shift reading that's important for you to absord 

4) what values and soft skill sets to emphasise

Here's my sentence for an optimal candidate (what you're trying to demonstrate to them):

"Someone who can approach a complicated problem and think + communicate in a structured way in the right context+objective of the case, while being personable, adaptable, and coachable, so that, ultimately, the interviewer can see themselves working with this individual and putting them in front of a client."

5) what kinds of questions would be best for ME to ask at the conclusion of each interview.

Genuine questions. Have a conversation. Ask about them. Ask about the topic. No different to any of your past interviews! I have a list if you need ideas.

Final Note: Don't “expect” things

It's great you're doing your research! But, just remember, actual interviews are fluid/dynamic and depend on the person interviewing you.

Just as a reference, check out how this interview with McKinsey went for one of my recent candidates (you know, the McKinsey PEI that is “set in stone” and you can “100% gaurentee these will be the 3 questions they ask”)