Also don't be shy about calling the school or the teacher and letting them know what your child is capable of as well as how they handle stress. My son gets stubborn when he gets stressed, the more problems he has, the more he says he can't do it, then that is the longer that he just won't try. You will also want to let the teacher know if this is the way your child works. As soon as my son's teacher listened to me and stopped telling him it was okay to trace his name, he realized he had to do it and hasn't had a problem with that since. When your child brings home papers showing what they did in school that day, take the time to look them all over.
Praise is a very important part of raising a good student.
Stress the things they did well, don't gripe about what they didn't. In a lot of classrooms, the kids are copying onto their papers what the teacher told them to, or what was on the board. So reinforce what they did at home to make sure they actually learn and retain the information. Go over their papers with them, print your own similar papers that they can do at home. This way you can answer any questions or address any problems early on before they become a deep seated issue.