If you have Warp a great way to make money:
Set your homepoint in the port of your home city. Go catch an airship to Jeuno, make sure to do the "Lost Item" quest. Find npc, return item, make 300 gil profit.
Now warp home, set your character to auto-run onto the ship, and go watch tv for 10 minutes.
Rinse, repeat.
After a couple hours you'll have several thousand gil for what amounts to no real effort.
Now invest that gil in a fishing rod and some bait and start fishing up moat carp.
Use the profit from the moat carp to buy gear and level up.
When you hit level 75, sell your character to a gullible noob, and use the money you get to buy gil for your new character.
Rinse, repeat.
After a couple of years you'll have several million gil.