Never mind, and take it easy.

没关系，别紧张。

Take it easy! Don't panic.

沉住气！不要惊慌。

Don't let your nerves get the best of you.

不要被紧张的情绪左右。

You'll never get the best of me !

你永远也赢不了我！

I have butterflies in my stomach the first time I met him.

She was a nervous wreck, crying when anyone asked her about her experience.

她是个极度神经质的人，有人问起她的经历时，她就哭。

When I first started college, I was a nervous wreck.

当我开始大学第一天生活的时候，我快紧张死了。

I don't want to seize up in front of the students.

我不想在学生面前紧张到僵住。

Your back may seize up.

你的背部可能会发僵。

Sit down and chill out!

坐下来冷静一下！

I should cool out a little, I guess.

我想我应该到外面冷静一下。