World 3 is fairly straightforward and easy. I found it easier than world 2 by a good bit. Just remember to use RB and collect scrolls when an enemy is in your path. Collecting scrolls replenishes your power, but just try to conserve power when you can simply avoid enemies.
For the world’s boss, simply use your attack power to send the boss’ projectiles (her fans) back at her. When you’ve collected all the scrolls on the boss stage, the scrolls will reset, so don’t be stingy with collecting them/ using your attack power.