How do you correct a vocal fault (that could be potentially harmful) when the student can’t comprehend what you’re telling them to do to change how they are singing?

Drink lots of water me myself I drink 8 glasses or more a day.
Don't drink to much soda, alcohol or caffeine because that can cause a raspy voice
trust me it has happen to me many of times.
Definitely don't smoke it will only make it worst.
Excise your voice on the daily I like to do it in the shower most
of the time. I even do it on the bus.

I've been on a hunt for these tips due to the change of seasons! On reddit, I was recommended a nasal spray, and it was pointed out how allergens can weaken the immune system, so being extra conscious of that during those times of year can be game-changers. Or should I say voice changers? Ha. I also stumbled up Seasonal37, which was made specifically for singers. Been working wonders for me, but it's been in combination with preventative stuff too, so who knows! Figured I'd share