The tiles only move down once for each time you shoot. No need to fire quickly, so take time to plan each shot for best advantage. The more balls you gather, the more powerful each shot becomes - a single shot with 4 balls eliminates a tile marked with a 4, etc.
I've been playing for a couple of weeks. You do not have to drag the ball or aim indicators to the box. If you simply click and barely point in the direction, the ball "fires". Obtaining extra balls is a huge advantage. Once you start gathering balls, try shooting at a very shallow angle, or up into a void so that the balls bounce around in the upper area among boxes more actively. I started with scores in the single digits and 20s, but am over 5,000 now. But how on earth others get the enormous scores hey do is still beyond me!