How to prepare for a Job Interview?

Well, first of all, you need to stay calm.
Keep in mind all you have to say and all you did to get there.
Search all you can about the company and make sure that you want to work there.
Practice in front of a mirror or with a friend, so you won't make anything wrong.
Dress something fancy.
Be polite.
Be honest with all you say.
Don't talk unnecessary things.
Thank the person that are talking to you.
Go home.