It helps to have a stable yoyo with a forgiving catch zone when first learning. Although I can do it with my Lyn Fury now, when I first learned it, I could only do it with my DM2 and I would fail every time I took out the Lyn Fury.
For me, a good next step was to get into position (split bottom then front underpass), and then “rock” the yoyo forward and then back before engaging the throw hand “up and down” motion. Even just rocking it back and forth will “tell” your finger what rhythm to expect.
Although tutorials make it look like the up and down motion creates the boinging motion from scratch, this is not true. The momentum has to be there first, and then the up and down motion supports and augments the back-and-forth.
In other words, don’t rely on the up-and-down to create the back and forth. It won’t work. And in my case, creating the back and forth by swinging/rocking the yoyo to start it up, worked well.
However, that’s not the place to stop. The momentum we’re talking about is best created by the motion of getting into position itself. The yoyo should gather momentum as you mount it in the split bottom mount, and you should carry this through to the underpass. For me, this means that coming into position, my yoyo is already going “forward” (it is back as the underpass is near completion, ready to move forward as the fingers are in place), and then I immediately move into the down-and-up of the throw hand in order to support and build on this existing momentum.
It’s good to understand why the throw hand moves up and down. Just like with Eli Hops, you are simply accomodating the laws of physics. Picture a yoyo swinging with no intervention… the yoyo will move in an arc, right? But with Boing-e-boing, the yoyo moves in a straight line back and forth, so:
As it moves either forward or back, the throw hand finger moves down to give it the necessary slack. As it comes back to the middle, the throw hand finger moves up to its neutral position, or where it would be if the boing-e-boing wasn’t in motion (plus a little bit extra to add more energy and keep it going). Thus, you need to go up-and-down twice for every full back and forth!
It’s “good” to understand this, but it’s not necessary… in truth, what will probably happen is that you will hit it once and the feel for it will just “click”… and you’ll start to get better and more consistent with it.