Doing a mock interview is great advice.  I just did a mock today, and got some interesting feedback!  My interviewer told me to be cautious about my eye contact.  She said that I tend to not break my gaze often enough, and that it's intimidating to speak to me.  I never would have thought of that, but it makes perfect sense.  In a stressful situation like that, I'm concentrating so hard on what the interviewer is saying that I do intently look at them.  My interviewer suggested that I take a small bottle of water with me, so that I can break my gaze periodically to take a drink.  That way, it will seem more natural that I'm looking away, instead of me purposefully trying to awkwardly look around the room once in awhile.
Anyway, I thought that was interesting advice.  Maintain eye contact, but not too much!   🙂