Honestly I sometimes wonder how I did it, because my cats listen to me and rarely do something I don't want them to.
Im firm with them, never loud, never hit them or push them. Consistency might be the key. Always tell them no the same way, as many times as it takes. I'll give them something else to play with if they're ripping something up too.
Exactly this. Had a friend struggling to teach a kitten. He had the habit of sounding stern, but not following through, simply pointing like a threat. It even confused me, let alone the cat
Within 1 hour of me consistenly spraying the kitten with water and using the same tone, the kitten started to hesitate when wanting to jump on the counter. It learned not to do so quickly after that.