Hi,
A very interesting and wide question of course.
I once taught a 7-year old piano student together with my tutor who was teaching me how to teach.
I somehow really enjoy teaching children and I think for them the lessons and time spent with me are also interesting.
Why?
I think because I take them as equal. I talk to them really what I think and discuss things. It really changes them. I really try to understand them and am interested in them.
Because of my tutor and pressure from school the student one moment decided not to continue learning.
I just talked to her. Asked why. I told that interest comes from inside and can not be forced. Told that playing the piano is really playing and later she would be sad that she once stopped learning. And tried to make it as interesting and colorful as possible at the same time tried to give her recognition for everything she achieved. She is really talented. So the problem solved.
I saw how school system and parents and all this started to force the inner interest and joy to fade and how all this learning in an elite school and so on had a ruining effect on her because of enourmous pressure. But yes, with piano it went well. I also had a long conversation with my tutor who teached me how to teach

Long story, but my ideas:
1) Recognition for every little achievement.
2) Teaching through different images and pictures etc. instead of talking too much about dry and boring details.
3) Always staying positive and even criticising through positive side. You can say:" You did it wrong." or you can say:" You have a great opportunity to play this place even better."
4) Staying simple and sincere.
5) Taking child students as equals. Discussing things and respecting their opinion.
6) Guiding instead of ordering.
7) Giving an alternative instead of forcing the child giving up doing something.
I have never been strict or argued with children in lessons. And never had any problems.
Recently got a great compliment from a 8 year old boy student when he asked:" Why are the piano lessons so short?"
Just quick ideas also very subjective.
Hope it gave some insight.
GL
Jaak