My favourite technique is after the initial two ball crosses was for me to stand in for their left (or non dominant) hand.

You stand slightly behind your pupil and get them to put their left hand behind their back and you put your left hand about where theirs should be. You give them one ball in their right hand and then you start the pattern with two balls.

Most people are amazed to find themselves juggling at this point. Yes, you are correcting their mistakes but it gives a real feeling of juggling for them. Most people manage 10 catches quite easily at this point.

Once they have the hang of that swap sides. This one is harder, don't do it too long before setting them off on 3 and they can practice themselves from here on.

I have taught 100s of people to juggle like that :-)

Some of us had a juggling party at a lake. All amateurs, i.e. few could manage much with clubs. An international juggling award winner (don't remember more than that) found out, joined us, and had a number of us partner juggling flaming torches pretty quickly, and kept pushing us into more and more techniques. The quality of the coach matters!

That's a neat approach! It's not really the same, but it kind of reminds me of an interview they did with Michael Moschen (the guy who performed the contact juggling scene in Jim Henson’s movie Labyrinth). He talked about how difficult it was because he had to thread his arms underneath David Bowie’s, so he couldn’t actually see the acrylic ball while he was doing the contact juggling.