There is not a great deal of combo strategy to be had. The game is more skill-based in quickly (very quickly, mind you) recognizing lines to clear one after another, otherwise known as chaining. This rapid succession of clearing lines scores the same as comboing.
Also, your strategy should be dependent on the mode you are playing. In Normal mode, you'll be leaving many points on the table by haphazardly clearing lines; ideally you should step-child one animal and continue clearing all other animals until you're forced to clear the neglected animal. Conversely, in Time Attack, the majority of points are in the later level-clear bonuses and later level comboing/chaining, so you'll want to progress as quickly as possible.
