That's really good that you are flying down for the interviews (out of schoolies) =]
Btw as for tips... Hmm... I have only ever been to THREE interviews in my life >_> The first was a group interview (which I made it through), then a one on one (where I answered the stupidest answers and got knocked back), and then a group + individual interview at the firm I wanted most (I'm working here now^^)... So my best piece of advice is just to prepare for it. Practice with friends/family- or even use one of those interview study guides (like with sample Q's and tips for dress)... but in short, don't be rude/disrespectful, shake hands, give 'em a good look in the eyes and a warm smile =] I think it'll be worth your time if you spent an extra hour or so getting ready (get your suit nicely set, do the hair a bit, shave, clean up, ensure no bad odours, etc..)~ after all, there's no point in being the most qualified candidate on Earth if you smell bad, look horrible and are wasted.
Best wishes in your interview though & make sure you are you. Beconfident, but not cocky. Confidence is great, but if you don't know something, there's nothing wrong in asking for clarification. I've heard of people who have asked "What's an auditor do?" in their 2nd round interviews for Big4 Accounting- and this person got the job. So don't worry too much- just be you =] (assuming that you aren't a cocky person!)