Cueing is so important. It can be the difference between great engagement and recovery of core related issues and just engaging other local, overworking muscles.
I have lost count of the number of exercise classes where I've vaguely been told "Pull your belly button to spine". When? All the time? When I'm inhaling? When I'm exhaling? Fortunately as a physio I know what I should do, but many other people in the class must be totally confused!
Key aspects for core rehab are:
Use your exhale to engage the diaphragm and reduce intra-abdominal pressure.
Make sure a pelvic floor contraction is included.
Make it bespoke! People do not respond the same way to an exercise. Check their engagement - how well are they achieving tension? Is tension generated along the whole of the TVA, or is one area better than another? Can you change the cue to improve the engagement?
I'm constantly playing around with visualisation and cueing to see what works best. We're not robots, everyone is different, but that's what keeps the job interesting!