For me, I have found that partaking in any chance I have to write has increased my writing dramatically, be it grammar or style. When I run into some sort of question or issue, I simply Google the matter and find a multitude of grammatical websites that prove to be useful.
If you are concerned about law review, I wouldn't be too worried about it. In my experience, many people on law review are not the best writers. Instead, they excel at the ultra practical skill of obscure bluebooking. Even if someone gets published, he will have his work reviewed enough by others to have all grammatical issues resolved in the end.
I believe that writing is a lifelong journey, and your style and skill evolves with frequent exercise.