However much preparation you do beforehand, going into an interview is usually slightly nerve-wracking. But do not make the mistake of thinking that, after entering the room, the situation is out of your hands. There are still a number of techniques you can use to make sure the panel sees you in the best possible light.
This is not just about speaking calmly and audibly - although both of these things are very important. But it is also about letting the panel know what point you are making, and why. For example, if you recount a story of a particular problem you faced in a previous job, do not assume people will guess the relevance. Instead, make a point of deliberately linking what you say to the requirements of the job.
One way to help make sure you stick to the point is by keeping your answers to within a rough time limit. Although there will always be exceptions, it is unlikely your answers will ever need to be much longer than two minutes. Also, structuring your answers with three or four main points will make life much easier for the interviewing panel - which will be good news for you.
Of course no-one wants to appear over confident, but the fact remains that this interview is about you, and your answers should reflect that. So avoid saying 'we' when you really mean 'I'.
Fleshing out your points with examples from your own experience is important, not least because it shows an ability to learn and develop. It also helps you steer clear of vague statements, which rarely go down well with interview panels.
However, talking about your personal experience is not an invitation to say whatever pops into your head. Do what you can to base your answers on individual experiences, but be aware of slipping into irrelevant anecdotes.
Not all interviews are the same, and you may find yourself surprised by something, such as the questions themselves, the tone of the interviewers, or even the seating arrangements. As a general rule, try to keep in mind that things may not proceed exactly how you imagined they would. But this can be a good thing - you will get the chance to show your ability to think and act on your feet.
Remember, the most important part of an interview is to sell yourself, and to show why you are right for the job. But try to show the 'real you' if you can, not just someone who can learn answers to interview questions parrot-fashion. Whether you get the job will be as much down to your personality and enthusiasm as it will to your skills and experience, and the answers you give. Good luck.