1.

Buy items permanently as soon as you can afford them — rentals are lost on death.

2.

Dungeons can be done in almost any order — item rental enables full non-linearity.

3.

Maiamais are hidden under rocks, in caves, and behind merge paths — find all 100 for upgrades.

4.

The Tornado Rod is essential early — it launches Link upward for hard-to-reach areas.

5.

Lorule Castle (final dungeon) uses all items — make sure everything is bought and upgraded.