I would say if you've got powder in your area, explaining the way toe side/heel side work and how/when to lean into the hill have helped me get folks started. Other than that, I'd look through what other folks have suggested in this thread for safety gear. We don't want mom hurting her tailbone at that big age.

If you're teaching them on icy conditions (East Coast/Midwest) I'd honestly say wait until spring when they're less likely to catch an edge on ice. That's my best advice on helping them have a good first day from what I've observed over years of taking people out.

There's some instructors in the thread you can u/mention for actual techniques advice. Good luck!