Leave the one in the center alone for now. It will get out eventually, but until then you want to concentrate on the really large ball. It might look really slow for now, but the smallest incarnations are extremely fast. Take it out quickly and then concentrate on the center ball.
There is a good shot location just in the center. But you need to be careful as the shots just next to here will be really short and most likely not stop anything hitting you.
Try to leave one of the large red balls intact so you can concentrate on getting rid of the other first. It will most likely bounce in the center between the two lines. Power-ups should ensure you can get this done quickly.
This one is really easy, unless you screw up. The block just above you can be shot. Don't do this.' It is a perfect safety net. Shoot by just next to it and only the smallest balls will come through, once in a while. Take care of any that get out and then keep shooting into the basket.