For an easy way to get the Thief job, have at least the level 2 Black Mage. When you pick up the rare item from Merchant X (Thief's Memory) inside the Guardian of Flame dungeon (the glowing ring on floor 11 that will either take you to a duel or to a shop), walk away from Dungeon Hero X until he is close enough to use Sleep on. Then, run to the stairs while trying to run around the south side of the shop to make this easier. If Dungeon Hero X is gaining power, move two steps to the side of him. His beam is three spaces wide and goes very far. Keep Dungeon Hero X asleep all the time, if possible. This may take several attempts but it is much easier than any other way. If you get Dungeon Hero X asleep at the very beginning, you may be able to run directly to the stairs without going south around the shop, but this is much riskier. Because Dungeon Hero X can move much quicker than you, try to stay as far away from him as possible, but also making sure he is asleep.
Complete the game to unlock the Chocobos's Memories standard dungeon that can be accessed through the Chocobo statue at the park and the Croma's Future special dungeon that can be accessed through Croma at Stella's house.
At about Chapter 4, speak with Dardola at Dardola's Dining. After the bell rings, he will lose his memories. Help him by completing the dungeon. As a reward he will allow the jukebox in his shop to play music.
Unlock the following jobs by performing the corresponding tasks:
JOB - HOW TO UNLOCK Black Mage - Reach 10F in Guardian Of The Flame. Dancer - Enter "Pirouette[Music Note]"(case-sensitive) as a Romantic Phrase. Dark Knight - Defeat Croma Shade in 30F in Guardian Of The Light. Dragoon - Beat Meja's Memories. Knight - Beat Freja's Memories. Ninja - Beat Volg's Memories. Scholar - Defeat the four elements in 20F in Guardian Of The Water. Thief - Steal the item behind Merchant Hero X in his dungeon shop. White Mage - Beat Pastor Roche's Memories.
After helping Freja get her memory back, go to her place and have her hone your equipment to make it stronger. Before you start to hone, bring at least a couple thousand gil and save the game. When you get to the point where it says that it is at the maximum level and you can still hone it, you may want to save the game again; when Freja tries to hone it past it the maximum level it will have a greater failure chance. If that happens, reset the game, load the saved game, and repeat until she makes a perfect hone. This may require several attempts.