To score critical hits very easily, first you must have a Barbarian warrior, such as Urlan. When you have enough points, learn the morph into bear move and bring Urlan into combat. Turn into the bear and attack someone using the move called "Bite"

Timing this move right is critical and easy, just press A as fast as you can. Even at extremely low levels (1-3) it can dish out up to 80 damage.