Practice. There is nothing else that can prepare you better. Assume that you will fail the first 5 interviews and use them to learn. After a while, you get the hang of it and learn how to fake it for the real thing.
And remember, you do your best when you don't care about the job. If you do care, your nervousness and desire to impress will be perceived as incompetence. And at that point, you're just sabotaging yourself.
And remember, you do your best when you don't care about the job. If you do care, your nervousness and desire to impress will be perceived as incompetence. And at that point, you're just sabotaging yourself.