Comment by MalcolmDiggs

The more you do it, the less nervous you'll feel. I'd suggest lining up a series of low-stakes 'practice' interviews (10 or more of them). Real jobs at real companies, but the kind of jobs you don't particularly want, and the kind of companies you wouldn't normally apply to. That way you won't feel any pressure to perform well; and you'll get practice interviewing. And who knows, you might luck into the perfect position just by chance.