An often overlooked part of the interview process is fielding questions and, being heard to ask a lot of questions yourself. Granted, the lions share of the interview maybe dedicated to selling your experiences against a raft of different scenarios you may find yourself in should you get the role, however, you'll be kicking yourself IF you walk away from the interview not having clarified anything and everything.
I'm as guilty as anyone of not having my questions written down beforehand, relying on a) a good memory and / or b) I will make some up when I get there. Trust me, use a pen and paper in advance of the interview. Jot down a few things that you want to know, need to know or, seem even remotely relevant to the position for which you've applied. Although the 'there is no such thing as a stupid question' is kinda true, use the questions you ask to demonstrate you've researched the role, company or even, the person that's interviewing you.
Though it's one step short of stalking them, get a print out of their linkedin profile - highlight any key points on their profile(s) that may be of interest or you feel that are pertinent to bring up during the interview. It's often surprising how many shared contacts you have, things you've both done, people you've worked with or work for let alone projects you've been involved with etc etc
Even today, didn't quite have my thinking cap on for the ... where do you see yourself in three years? ... If we rang some of your past colleagues or co-workers, what would they say about you? ... When you get up in the morning, what task do you dislike the most? ... What do you see youself achieving in the first six months? ... Given the amount of stakeholders you'd be dealing with, who would you tackle first and how would you approach this?
When on the train back from London this evening, the post mortem will continue - what went well and what could I do better next time?