If you have to teach grammar, teach it authentically. Use models by native speakers for native speakers, and break down
Presentation. Attention. Co-Construct an explanation. Extension activity.
P.A.C.E. kind of reminds me of my English methods class. We learned that isolated explicit grammar instruction was one of THE least effective things you could do in a class, that modeling (preferably from real books or students' own writing) was the only way to make grammar stick. P.A.C.E. struck me as a nice systematic version of this approach, and so I've been experimenting with P.A.C.E. since the year before last.
More recently, instead of using a First Aid manual (authentic, but not so high-interest) as a source of authentic sentences to highlight grammar functions, I used lyrics & literary excerpts.
Still more recently, I dusted off this method again in conjunction with my La llaman America unit. Once again, I'm using it to illustrate object pronoun usage, but first, we reviewed something familiar that seemed to be giving students trouble when they were biographers for classmates, using America's first page as a model: verb endings. So I made this powerpoint--with directions for how I want P.A.C.E. notes set up (since we have a "copying crisis" on at school--otherwise I could just distribute pages like this one, which, of course, I can still make available on Edmodo to enterprising students).
In the past, I have been lacking in the "Extension" department, so the latest addition involves students once again using America as a model, but this time, switching a paragraph of her story to 1st person. Though the P.A.C.E. focused on 3rd person, as the book does, my pre-assessment (a really uncreative verb quiz I kind of invented on the spot) indicated most people get how yo forms work already. And after all, they were extending what they learned, right?
We dipped our toes in the object pronouns lesson today, having completed model notes on something more familiar first. There are a lot fewer examples for Presentation this far in the book, and the Extension activity involves making a list of people one encounters in the morning before coming to my class and what you did to them (like greeted, smiled at, etc.) Obviously I'm still getting the hang of making an effective Extension activity, and I think I'd like to expand to include an interpersonal Extension in addition to the semi-presentational one to be included in the notes.
An old, semi-related tweet: @SECottrell says "It's not whether you teach grammar- it's why. Come to a consensus on your approach to grammar. Purpose: avoiding miscommunication."