First, Learn to Toss One Ball
"That's easy!" you may scoff. But two of the most frustrating mistakes are to toss the balls too low (requiring you to juggle at a manic pace) or too high (resulting in a loss of control).
So first, take the zen approach. Take one ball in one hand, and toss it to your other hand. Repeat. Repeat. Repeat. The ball should follow a nice smooth arch, cresting at about the same height as the top of your head. Get this movement into your muscle memory, and then pick up a second ball.
Two Balls: Take it One at a Time
Step One: Hold one ball in each hand.
Step Two: Toss the ball in your right hand, in the same arch you were using when you only had one ball.
Step Three: As the first ball reaches the top of the arch, toss the ball in your left hand.
Step Four: Catch the first ball as it drops into your (now empty) left hand.
Step Five: Catch the second ball as it drops into your (also empty) right hand.
Now: Repeat, repeat, repeat. Then, do the same thing, but start with the ball in your left hand. Repeat. Repeat. Repeat, until this movement is comfortable on both sides.
Three Balls
What's so special about three balls? Take a look at Step 4 above. The orange ball is just cresting the arch to the right, the point at which Chalk Man would like to toss the ball in his right hand - but his right hand is already empty. Add a third ball into the picture, and you fix that problem - Chalk Man can go on juggling indefinitely.
Juggling three balls uses the same movements as 'juggling' two balls: There are, in fact, never more than two balls in the air. So in principle, it's not harder to juggle three balls: It just lasts longer. It's all about stamina... ;-)
Step 1: Hold one ball in your left hand and two balls in your right hand.
Step 2: Toss one of the balls in your right hand, keeping ahold of the other one.
Step 3: As the first ball reaches the top of the arch, toss the ball in your left hand.
Step 4:
Catch the first ball as it drops into your (now empty) left
hand. At the same time, toss the ball in your right hand.
Step 5:
Catch the second ball as it drops into your (now empty) right
hand. At the same time, toss the ball in your left hand.
Step 6:
Catch that ball as it drops into your (empty) left hand.
At the same time, toss the ball in your right hand.
Step 7: Repeat indefinitely. When you do drop a ball, start over. Practice until comfortable and rhythmic.
Now: Have fun!