One of my former students is deathly afraid of failure. Sadly, this stunts her creative growth and keeps her from being great.
Fail. Eff up. Guess. Make shit up.
There are no wrong answers. And there are a whole bunch of right answers.
Never be afraid to try, to make a mistake, to mess up.
That's how you'll grow and get better as a creative. That's how you'll learn.
Plus, if you're in portfolio school, this is your time to make a damn fool out of yourself. This is your time to fail and to be wrong. This is your time to fall flat on your face.
It's not like they can fire you.
One of my personal mottoes is "What doesn't kill me will strengthen me. And this won't kill me."
So if the only real failure is death, and if this (whatever it is you're afraid of) isn't going to kill you then what do you have to lose?
Related reading
Fail Big
Don't "I don't know" me
What if
Make it Up
Dealing With Death