A lot of these imperfections seem minor to me, like a tear in a piece of paper she was writing on, or a letter she didn't write correctly. She is very outgoing and very smart; I don't want to squelch her spirited personality, but how do I deal with her frustrations? I try to give her suggestions on how to fix these things, but she doesn't want to have anything to do with that, either. Help!
An "audience" often serves to keep an upset going. If she asks for help, you can certainly make a suggestion or offer an item (like tape for the torn paper), but if she rejects your offer, then calmly repeat your solution and pull back. You see, she may not be looking for understanding, but rather for you to "make it perfect." You can't, so she gets irritated.
This is a good time for her to try again and then accept the best she can do. Afterward, she gets a little praise from you for the effort -- not necessarily for the finished product. You will not be squelching her, but helping her to calm down and to like herself and her own effort. You may have to listen to some screaming at first, but she'll live. Don't play into this; her teachers certainly won't.