I thought it would be great to accumulate a few of the best practices you use when introducing people to the sport and teaching them to fly a trainer for the first time.

Here is a quick start...

1. Start by working to keep the kite in the air going back and forth in the middle of the wind window.
2.Stay away from the edge of the window. The kite will stall and you WILL dump it.
3. Keep your arms out straight in front of you.
4. Resist the temptation to oversteer, pulling the lines too far when trying to turn. With most trainers, you just stall them.
5. Let me show you how to roll up the lines and pack my kite. (In other words, don't do it when I am over helping someone else. Yesterday I spent 25 minutes untangling lines that a helpful spouse coiled up for me. Aargh, I hate it when that happens!)
6. Make sure no one is down field. Kite lines can cut to the bone.
7. Don't grab the lines. See warning above.

What have you got?

Can't stress #'s 5 and 6 enough. Lol untangling lines worst thing ever. Also #6 I chase people down to explain why you NEVER go between a person and there kite while it is on the ground.

How about wearing flat shoes with little or no grip especially on grass. Boots can result in a bionic run to faceplant.

"It's riding the bike, not driving the car! You drive, you crash! Ride the bike!"

is what my instructor was yelling at me until I got it....It has served me well many times since then.

Here help me unpack. (As your unpacking explain what each thing is and what it should do/is used for.)
Ok your launched good job... now let go and see how the kite killers work.
Just focus on keeping the kite in one spot.
Keep your hands together, imagine that you are wearing hand cuffs.
Elbows slightly bent they will help you absorb the gusts.
Start moving the kite back and forth.
Lower.
Lower.
Lean back let the kite pull you, don't fight it.
Loop it.. but when you do make sure that once you start don't second guess yourself. Keep the kite turning untill it's facing back upright.
Having fun yet?
The usual response :D
Now loop it the other way.
Fantastic!

also if using kite killers. every now and then let handles go.

Just so you know the feeling.

Safety is paramount

Actually I have found that the best thing to do with a beginer is teach them NOT to fly the kite but to control it.

I ask them to just keep the kite under control at zenith 1st. For 2 full minutes at least.

This teaches them to keep their motions small + think ahead without big mistakes waisting time. Setting the important reflexes . + finding out if they are adding unwanted brake action. Then when you ask them to start flying it a bit they have figured things out and do better at it.

I have found this not flying at 1st thing to work very well !