Find here / write you own spell. Do what you will.
However, this will not guarantee success or flourishing. You still have to specialize in what the job is about and be prepared for the interview.
Yes, a spell certainly can give you more mental confidence.
However I recommend to specialize in your subject very well, which gives you a vote of confidence as well.
Confidence building techniques are all over the internet, have a look and try them as well.
Also it's helpful to wake up and know that you're going to have a super day. :)