Just to give you a little tip preparing for the interview, many firms now use competency based interview so you have the opportunity to provide examples from the experience you've had - not necessarily in a working environment.
For example one of the competencies they may be trying to test is problem solving - what they are looking for in the answer is specific examples from your own experience.
So start writing down a book of examples as you can never remember when you are put on the spot, so as something good happens write it down. set it out like this
Situation - what the situation/problem was at the beginning
Task - what you felt the solution to the problem was
Action - what you did (keep this specific to you, they don't want to know about your next door neighbour helping you, they want to know your imput)
Result - what the ultimate result was.
Word it in the same sort of way, it makes it easier for them to sift through later.
Example -
Situation - you were struggling with a debussy duet, getting the timing to meet with the other person.
Task - identify exactly which section was wrong, and what was wrong with it, eg, you were unable to get a timing section correct that had quavers against triplets going in between each member of the duet.
Action - I (always use I never we) double checked the notes, spent time working on getting the 2 against 3 independently then arranged a time to get together with my duet partner so we could work it through slowly together.
Result - We won the duet part in a festival
Really silly example but you get my drift!
Start a file with loads of examples that you could use. You probably won't be able to take it into the interview, but you're more likely to remember it if you've written it down.
The other thing is to reiterate what Janexxx said, always call for feedback, it identifies whether you are doing things wrong - I always call, and have only once been refused, I found out later from a friend that the guy was intimidated by me, which didn't surprise me he was useless as an interviewer