Unlimited items:
At times, you may approach an item and press [Space], before continuously tapping T to obtain an unlimited number of that item.

Unlimited keys:
Save the game after entering a dungeon or cave. Move through your location until running out of keys. Restore the game to resume with the doors remaining open and a new set of keys.

Unlimited bravery points:
Jump on the turtle and keep attacking it.

Increased luck:
Locate the Sorceress on the island with the Crystal Castle. Use the "Ask" command several times to increase your luck to 65.