Find 3 balls that are heavy for their size. Something about the size and weight of a small apple is about right. You need the weight to properly feel them land in your hand. Lacrosse balls are great and not too expensive. And they come in different colors, which makes them more fun to watch. Tennis balls are too light; golf balls too small; softballs too big. The soft juggling balls they sell are good though a bit expensive. The advantage is they don't roll away when you drop them. But if you practice standing over a bed, the harder balls won't roll away either, AND you don't have to bend over too far to pick them up. Plus if you are practicing with apples, they won't get so smashed up.