Don't put yourself under pressure: your interviewer has a position to fill, you are perhaps the solution.
Try to identify what interested him in your CV: internship? linguistic capacity? ....
Try to make your interviewer talk, reply precisely to his questions, repeat the sentence if in doubt
Ask questions on the company, even if you already have information from outside sources, so as to show your interest in them
Don't ask for your career plan straight off - prove yourself first
Adapt your replies to match the person conducting the interview: an human resource manager is not a computer engineer. Don't drown him in technical details, a Line Manager will be able to reply to your technical questions, but won't necessarily know everything on the LPP....
Don't leave the last person to interview you without knowing what will happen next: when should you have a reply, will there be a second interview if everything is positive? If the planned date elapses, you can then take the initiative to telephone.
Be prepared with references: last employer or in the case of juniors: professors or the person responsible for your internships.
