wantobe - it's been a while since I went through the Airways system, but I've had a bit of recent experience with ab-initio recruitment. At an interview, your task is to convince the interviewer(s) that they should take you over someone else. You don't want to try and bullsh*t them, but they don't have any secret selection tool and they will be comparing your answers against the other candidates.
You have made a useful start by soliciting advice from the crusty old buggers on this forum! I suspect many of them would agree that sound advice for an interviewee is to be yourself. However, do heed conventional practice: be on time, and dress tidily. It is an unfortunate fact that first impressions really do matter in these situations, and can influence the judgement of interviewers if it comes down to choosing between two candidates, for example.
Other than that, listen to the questions asked and have them repeated if you miss something. Keep answers concise and to-the-point. One of the earlier posts mentioned having specific examples to demonstrate Airways values: good idea. It is valuable if you have particular experiences you can talk about which demonstrate how you a) coped with pressure b) remedied a mistake and learned from it c) have applied yourself to achieve a specific goal or milestone. These are fairly standard questions; they allow you to talk about something familiar to you and therefore to "open up" a little. the more well-rounded you appear as an individual, the more likely you will stand out as a suitable candidate.
That's a quick summary, and hopefully not too dissimilar to what you have already heard. Like slackie says, it's a great job for anyone with even the slightest interest in aviation. And by the way - costs and lack of pay aside - Airways is still a pretty good place to train.
Good Luck,
Pig