Some tips from a music teacher with decades of experience. Here they are in no particular order.

1. Show an interest. Sit with them during lessons and supervise practice until they find their feet.  Keep it light hearted, but  short. Maybe just 10 minutes of supervised practice a day is enough.  
2. Learn about their favorite drummers and share time together watching and learning together from YouTube videos. If they don't have a favorite drummer help them find one.  Start with music they enjoy, identify the drummer and then explore the drummer's discography. 
3. Help them set up their practice space so that it is easy to practice. 
4. Talk with the teacher, show them you care about the progress of your child. 
5. Let them play too, practice is hard work. I suggest in the beginning 70% thrashing about, 30% practice. As they becoming increasingly emotionally connected to the project adjust the ratios.  (I personally over practice. In 2021 I promise myself I will thrash about more. )
6. Be sure they play an instrument that works. 
7. Help them set up the instrument properly. If you don't know how, consult a number of YouTube videos and ask me for help too. The videos below will get you started. Compare the angle of their thighs.  
8. Remember kid's want to  play music, keep it fun. Never punitive. Nothing sucks the fun out of a children's activity than an over zealous stage mother, or hockey dad.  I'm sure you met them.  Let's help the child associate drumming with fun and excitement the odds of success go up greatly. 

If I can help, call me.

David

There are lots of thoughts out there on this subject. Should I sit  high/low, sideways?(just kidding). Should my cymbals be high/low? I won't settle that here, but I invite you to check out https://drummagazine.com/how-to-set-up-your-drum-kit-for-comfort-and-efficiency/ 

Last night I dreamed I met Billy Cobham on the bus. He was living in Toronto, we struck up a conversation, hit it off right away. Two musicians sharing stories: journeyman/master.  He sets up like this: HIgh.

Travis Barker of the rock band Blink -182 sets up like this: Low

So, please have a look at the article through the link above. Today, I will be exploring some alternative set-ups on my kits. myself. 

The goal is comfort and  and ergonomically healthy set up. 

David