Here’s the best advice that I can give you in preparation for your CFI checkride. Show up prepared to teach. If the designee/inspector is doing his or her job, then he’ll be looking for you to do what’s expected of someone testing for an instructor rating: teach!
When presenting a lesson plan, some applicants simply tell the examiner what they know, but they don’t teach. For example, they’ll present a lesson but they won’t stop at the appropriate places and question the student (the examiner in this instance) about what’s being taught. Not teaching but just telling is enormous mistake to make on this ride. After all, isn’t that what good instructors do? Don’t they explain and demonstrate, followed by some student trial and practice with a review and evaluation at the end of the lesson? Isn’t that what the teaching process is all about? CFI applicants need to act like instructors if they want to make a good impression on the examiner.
So during the oral or the practical portion of the exam, explain, then demonstrate. Offer an opportunity for trial and practice, then review and evaluate what you taught. If the designee doesn’t want to see you teach but is only interested in your knowledge, then let him or her make this call. Don’t assume that simply demonstrating your knowledge without teaching it gives you an advantage on a CFI checkride.