Writing by hand mode-shifts the brain. A keyboard under the fingers makes it easy to add more and more — the click of the keys is the wind at your back. But the constrains of the printed page make adding indefinitely an impossibility, while subtracting is simplicity, slashing is satisfying.
Teaching invariably means reading more writing by people who aren’t professional writers. The result is a sharpened awareness of writing gone awry: typos, extra words, bloated sentences, meaningless filler, adverbs.
(Yes, my writing has improved, but it is far from perfect.)
There are numerous causes, but the solution usually involves what Grey recommends above.
Well, step one is getting writers to read what they’ve written in the first place.
The next level is printing it to read with pen-in-hand.
Reduce. Simplify. Clarify.
It also helps to read what you’ve written aloud. That’s an old David Sedaris trick, and a great way to find problems with rhythm, clarity, or structure.
NB: For the record, I’m not printing this or reading it aloud.