Strategy
Shoot your ball at the wall of balls coming down. If you need a certain color to create a combo of three matching colors and the game keeps giving you something else, create a cluster of several balls. Shoot three of the same colored balls at the top of the large cluster to create a group of three, causing them to disappear. The large cluster connected to that group will drop off the screen. This is a good way to get rid of unwanted colored balls without it building up quickly and causing you to lose that round. Aim your shooter at an angle to get your ball where you want it by bouncing it off the wall. This works for hard to reach places to shoot your ball.
Increasing Your Score
The first few levels are very easy to conquer in a short time. Build up your score simply by keeping the level going. The level ends when you eliminate all the balls in groups of three until there are no more left. Slow down with shooting balls to create groups of three. Keep adding more balls to the wall coming down since it moves slowly. You have plenty of time to create more balls to be grouped together in a combo of three before the wall reaches the bottom of your screen. This will help build up your score faster than if you hurry and eliminate the groups of colored balls to end the level. It is time-consuming and will make the levels last longer, increasing your score.
Level Up Quickly
If you are worried less having a high score than seeing how far you can get in the game, then you can work on eliminating the colored balls quickly. Shoot your balls effectively to create the groups of three and causing the balls to disappear and clear off the wall quickly. After a few levels, more colored balls are added to the mix and the wall starts to fall quickly. Shooting precisely will eliminate several balls in groups of three or more and dropping extra balls off your screen connected to the disintegrated groups.
Bonus Points
If you shoot your balls in a pattern of grouping them together with more than three balls, this builds up your score with bonus points as well. Shoot your balls to match two of the same colored balls together. Shoot a third ball of the same color just a ball length away, leaving room for a forth ball to connect them together. Shoot a last ball of the same color into the middle of the single ball and the group of two, connecting them and gaining bonus points as they disappear.