I decided to record a video of what I was doing. It was not pretty.
My arms were all over the place: I was reaching from side to side and I was reaching up to grab the balls.
I found a video online that has been helpful: Basics of Ball Juggling : How to Hold a Juggling Ball - YouTube
He says: "The basic idea is to throw the ball as high as your eye to your other hand. You’re throwing the ball to the hand, you’re not bringing your hand up to catch the ball.” This is the second most important piece of advice that I’ve come across.
Then I went back to the video that I posted in the OP. Near the beginning he says: "Take the time to master each step before going on to the next one.” I think that this is the single most important piece of advice, and it isn’t being emphasized enough. In fact, many of the written instructions and videos don’t mention it at all. They start with one ball, then two, then three but they don’t tell you to keep practicing each step until you master it before you go to the next step. And, of course, the question is: What does it mean to master it?
I’ve been practicing with one ball, with special attention to throwing the ball to the other hand, rather than reaching to catch it. This type of practice doesn’t require being near a wall, and it doesn’t require me to look directly at the ball. I know where my hands are, I know where I’m throwing the ball, and I can see the arc of the ball’s path. If the ball misses the hand, then I didn’t throw properly. If the ball reaches the hand, then I tossed the ball in the right direction with the right speed.
After tossing one ball successfully for a couple of minutes, it occurred to me that I should be able to do it with my eyes closed. I tried it and I was surprised but not shocked that I was able to catch the ball a few times.
I’ve also started practicing with two balls. The first toss is easy but the second toss is a bit tricky. There’s the additional issue of timing the toss, and, if I’m starting with my right (dominant) hand, then the second toss (which is harder) is with my left (relatively weaker) hand. If, though, I start with my left hand, the second toss is better.
Of course, after all this practice, I’ve tried juggling three balls. If I was merely trying to maximize the efficiency of my training, then I shouldn’t be doing this yet. But, I do want to have some fun, and it’s much more fun to juggle three balls than it is to practice with one or two.
I am much more consistent in the number of tosses that I can complete, and I’m rarely dropping a ball. When a ball starts to get away from me and I know that I can’t continue the pattern, I just catch it and start again. I’ve recorded myself again and I am smoother. My motions appear to be more efficient.
My target is to juggle for about 15 seconds consistently, meaning that when I pick up three objects (balls, oranges, apples), I have, say, a 90% chance of completing the 15 seconds. I’m not there yet. I need to practice more but now I have a clearer idea of what I’m supposing to be doing.