Coming out of high school, my writing was terrible. One of my history teachers assigned us ~10 page essays every other week. The class actually taught me pretty well to construct well-reason arguments with supporting research, but the only way I (or anyone else in the class) could produce that many pages that regularly was figuring out the _least_ efficient way to say what we meant.

My writing didn't really start to improve until college when I wrote some research reports for a semi-retired professor who took the time to wean me off my bad habits and write in a scientific style.