I do this 4-page grammar packet every year with my students in the first month of school to eliminate the 18 worst writing errors I see over and over in my years of teaching. We call fixing grammatical errors "slaying grammar demons" to lighten the mood, and it works! You can even spice it up by having students draw pictures of what they think "grammar demons" would look like!
The full lesson takes two days, and my students always say it was one of the most valuable (and fun!) things they learned, and that they still refer back to it years later!
I would start by giving students a Do Now to brainstorm WHY it's important to slay grammar demons. Besides the usual, "It will help you get better grades in school, more respect, and better-paying jobs," I always like, "You won't get dumped by a girlfriend or boyfriend who values strong writing!"
As you go through the worksheet (2 pages the first day, 2 pages the second day), do whole-class instruction of a rule, then have students fill in the worksheet section under it, encouraging them to be as fun, silly, and weird as possible to spice it up. Then share out a few sentences before moving on to the next rule. Add extra clarification or board examples as needed.
Reinforce these grammar rules with a quiz on them in the next week, then pull out this sheet again whenever editing essays (peer editing, self editing, or whole-class editing). Do at least one follow-up quiz mid-year on this. Keep slaying those grammar demons until they're all gone! :)