→ 40-50: Northern Thanalan - Ceruleum Processing Plant
Some people say to go here but when I get to lv 48 in Coerthas, I just stop the FATE farming and I focus in getting the full Class Hunting log from lv 1 to 50 which gives me 1 full level at Lv 48 and at lv 49 I do the class and job quests. If i need the last exp, i just go to coerthas to finish the leveling.

I recommend to you that you get at least Cure and Protect on and also you chocobo on the lower FATEs and leves and i don't really equip the Job's gem at lv 30, I just go full Lancer, Puguilist etc until I get to lv 49 to get the job quests done, I hope this helps and good luck.