Safety - I did what Puetz did - and it does put a dampner on (helmet, impact vest sunnies, and a lot of the basics & what if's)- I insisted on swimming competency and some squad training - + what they pick-up at nippers (Surf Life Saving - kids program) is invaluable.

Unless they have long arms, anything which helps their reach is important.
I found (still do) that having enough bar movement is critical.
Small(er) harness hook, shortened chicken loop, and when it is not too gusty trimming to get the best range.
I went with below the bar depower - but the trade off is it is harder to use compared too a toggle above the bar - but in learning mode they are not using it independently till they are confident on the board.
The seat harness I picked up is not ideal (an opportunistic buy but not really comfortable) but a good one will also extend their reach.
The 6m we started with has a couple of pulleys each side and a moderately complex bridle (SLE) - a few beginners later it is out of balance and although the kite looks good - it has lost its handling. The moral especially on a small kite - choose one with a simple bridal setup - so it relies on the kite design more than the bridal to fly through its stated wind range. - An Ozone is next on my list.
And on the fun / keep the interest up side, 1 of my kids who kites really well now (leaves me in 4 dead), kite tows the other each on their own board.


Cheers
AP