Dress well.
Before you go into the interview, spend a few minutes visualising yourself doing well in the interview. This will help calm you and give you confidence.
If you made it to the interview, then they probably already think you are capable of doing the job. The interview will mainly be to see what sort of person you are.
So you want to show them that you are a friendly, confident, likable person who will fit well in their team.
A company will hire a good team member with acceptable technical skills over a loner with excellent skills every time. You can teach people tech skills, but not personal skills.
Compliment something about at least one of the people interviewing you. But make sure you do it at different times. 'I love your tie where did you buy it?' 'Those are great glasses.' 'Are those shoes Italian?' things like that will endear you to them immedaitely.
Also compliment the company, again don't overdo it,merly aknowlege things that you genuinly like about the place. Or at least ask about it. 'How do you find working here?' 'Do you enjoy your job?' etc.
Whenever I go to an interview I spend more time being their friend than being an interviewee.
The result - I have
never failed to get a job offer from over 25 interviews, even when I was up against more experienced, qualified and skilled people.
Most of all -
relax.
You won't die if you fail. But
you will fail if you stress and worry about it too much.