For easy goings:

I just did daily hunts for lving up! o___o
Did this around 10x on my 2 chars o;
If you really do ONLY hunts from lv51 on (because chocobo lv51 is need) It takes around 4-5weeks and you hit lv60 ;D
You can speed it up a bit by doing those weekly quests.

I did nothing else to lv up! o; To busy with work last months.
Burning away leves x10 was also a help.