A spot of translation
Concise writing that gets to the point is good writing. One trick for concise writing that works wonders for bilinguals is to write what you’ve written in the other language then reverse translate it. Especially with Japanese you lose redundant words and phrases, the precise things you need to get rid of.
However, you don’t have to be bilingual for this. A similar effect can be brought about by trying to write what you’ve written from memory. That, and simply cutting out all the unnecessary words, of course.