BE HONEST but not too honest. You should never lie in an interview, but the unadulterated truth may not be a good idea either. Even if you left a previous job because your boss was unpleasant and the work was a dead end, you should find positive reasons to explain your departure i.e. - you wanted to learn new skills, play more to your strengths. Nobody likes a victim. Don't whinge.
PREPARE thoroughly. This means knowing your CV backwards and doing as much research as possible about the job and the company. Have a list of questions but don't mention money unless they mention it first.
ANTICIPATE the questions you may be asked: what is your greatest achievement? Where do you see yourself in five years' time. What adjectives best describe you?
BACK UP what you say with practical examples from previous jobs. If you are asked about weaknesses, resist the temptation to be too confessional.
It is much better for a prospective administrator to say for example, "I can be impatient" or " once I have started a task, I just want to get on with it", Avoid answers like "My typing is not very good or " I like a drink".
BE CLEAR about why you want the job. If you can't come up with a list reasons, you shouldn't have applied in the first place. A surprising number of people expect the interview to sell them the job.
LAUGH - appropriately - show your sense of humour - no one wants to employ a dry stick.
EXPECT the unexpected. You may be asked to do a test or suddenly give a practical demonstration of your skills.
DON'T be fooled by a vague invitation to drop in for a chat about a job. When you get there, your casual chat will almost certainly consist of being grilled on every aspect of your last 10 years by a three strong interview panel.