Leading Writing Problems
I read a lot of writing by doctoral students. I have never considered myself a grammarian but with enough reading the contrast between good and bad writing becomes relatively obvious. Furthermore, some problems are more common than others. In the Lingua Franca blog Ben Yagoda notes that of the writing problems he encounters:
“The leaders of the pack are wordiness, imprecision, poor or incorrect word choice, and spelling and punctuation errors.“
This entirely matches my experience. Fix these problems and people are much more likely to know what you are taking about.