You can't let your fears get the best of you, and you can't be a perfectionist. Accept that no one's perfect, and that it's okay if you mess up sometimes, and that it's a learning process. If you feel terrible every time you make a mistake, you won't function in society or at home. You need to constantly expose yourself to the things you're afraid of. Send resumés to places you don't really want to work for (like fast food places, etc) just so you can go to the interview and practice. Practice interviews with a friend, and get to know a company before going to an interview, so you have an idea of what they're about and how you can contribute. Also, be aware that the person doing the interview is probably nervous as well, since it's not often that the 'big bosses' do the interviews themselves.
Most of all, if you let the anxiety get the best of you, you won't succeed. Remember that anxiety is a normal thing, and that everyone 'suffers' from it. The difference lies on how you deal with it, and how you reprogram your mind in order to filter out certain thoughts and open the door for more positive ones. Remember: it's okay to feel anxiety. It's the body's response to fear/danger. Back in the day, it was the difference between getting mauled to death by a bear or making a safe escape (anxiety triggered endorphines and adrenaline, which in turn kept you alerted and able to run from danger). Since there are no such dangers in today's world, the mind had to adapt, and makes up all sorts of dangerous situations and scenarios when in reality there are no real threats.
Allow yourself to breathe into the anxiety, and focus outwardly. Focus on your breathing, and on how it's okay to feel anxiety. Don't allow your mind to feed on the anxiety and vice-versa, otherwise you'll be stuck in a loop. Freedom is letting go, just as you are, and to go with the flow of things. Have an interview? Cool. Turn your fear and anxiety into excitement and just being overall pumped for the new experience, knowing it will help you grow and make progress in life, as opposed to being too afraid to go.
Take a deep breath, put your shoes on and just go. Think less, do more.