Oh man, I know that feeling. I've dealt with it a ton myself.
For showing emotion, one thing I've tried to do is think of what physical action could showcase the emotions that go with the words being spoken. For example:
"Don't read my stuff!" She said angrily, taking the book back.
"Don't read my stuff!" She snapped, taking the book back.
She snatched the book from him, "don't read my stuff!"
It's all the same thing, but how it's written conveys a different level of impact for each one.