Keeping your finger on the screen, using multiple fingers, and slicing in a circle all reduce the chances of getting a bonus combo (especially pomegranate).
If a bunch of fruits are being tossed at the same time, start with the smaller ones first, as they fall faster and need to be cut more accurately.
It is not necessary to cut the fruit when it appears. You can let the fruit fly for a while, and cut it at one time when it meets other fruits or in a straight line, and the chance of battering is higher.