Be prepared to explain your client base. This includes industries and anything within those industries you might either have developed an expertise in, sizes of clients (sales volumes), and where you fit in on the engagement (who are you reporting to and who to you etc.).
This is especially important for managers and above. Make note of everything you're currently working on and be ready to go into detail.
Have examples of times you had a client technical issue. Be able to explain the issue and how you resolved it.
If interviewing for an industry group outside your current experience, have a fully developed reason why you want to move.
Be able to articulate what you are responsible for and how much time is spent reviewing opposed to preparation (compliance practices).