As a Thief, you can go for what my LS called the Stealth approach or the Backstabbing approach - Mithra make great Stealth Thieves, the strong points of their natural stats being enhanced by the Thief job and vice-versa, while Elvaan are the best Backstabbing Thieves, dealing the most insane damage of all races.
I remember somebody asking this before, so you might want to look up the thread. I said much along the lines then as I did now - to go Mitha if you want to be a regular Thief, or Elvaan if you want to be a Melee Thief.
Quote:
Elvaan have horrible dexterity and agility, the worst in the game in fact. Their mana also isn't great (worse than hume, but not as bad as galka), and they have less vitality than a galka. The only reason to play this race, that I can see, is because they look cool. There is another race that can outperform elvaan in every job.
That's utter nonsense. Couple Elvaan's STR with a Dragoon/Samurai Pentathruster. Enough said.