Your interviewers want you to explain to them why you're a good fit for their firm. That means you need to understand what law firms do, what their type of law firm does, what they do well within their category of law firm, and why their strength in a particular area or areas in the law matches your career aspirations.

So you'll need to explain what it is about finance or IP, and the firm's work in the area in particular, that has led you to apply. If you find that you can't identify an actual area of legal practice that grabs you, do more research or think again about a career in the law.

Remember, though, that your interviewers won't be expecting you to be an expert on your chosen area yet, and you don't have to commit to it for the rest of your career - this point of the interview can be a great time to ask some questions of your own, find out more, and clarify your aspirations - you'll be showing your interest is genuine by doing so.