I know that as an English teacher, I am constantly finding myself wanting to pull out my hair whenever my students use 1st/2nd person, "it," and contractions. To prevent this in my student's future writing, I taught this PPT, which teaches them how to avoid using all of these in their writing!
This can be taught for any secondary grade level--my 10th and 11th graders responded positively to this. I created a worksheet as well that is paired with the PPT. Look through my items and find the "3rd Person Worksheet" to download and give to your students as practice!