fight A LOT of fiends

or u cud save ur money XP

you earn plenty of guild,in the later stages of the game,you could always buy a cheat cd for ffx,wouldnt recoment it,as can ruin the game for you

A couple of tricks you could try, but you need to do some work first lol..

Rikku's Celestial Weapon the GODHAND Has the ability Gillionare, what it does, it doubles the amount of Gil earned after a fight..

You can customize your own to a weapon..You will need "30" Designer Wallets,

You can bribe, Defender Z, At Omega Ruins , you should recieve 5 for 846000 gil. He's also at Ruins Of Zanarkand, same price same amount. Also to get 60 Designer Wallets in one go, You need to have captured all the fiends for Omega Ruins area, In the Monster Arena Side Quest, Area Creations.

And The Omega Ruins is the Best Place. Go to the Omega Ruins, you will encounter treasure chests in battle. Steal from them do NOT Mug em.. If the treasure chest has nothing in it, it will turn out as a Mimic. If you defeat a Mimic you'll receive 50,000 Gil after the battle. But what's even better is if you have the weapon with the Gillionaire ability on it, you will receive double the amount. 100.000 Smackers.

Another way to get in some cash, you can repeatedly kill One-Eye at the Monster Arena, who will drop weapons with Triple AP which you can sell for Around 60,000....

Yup One Eye and Mimics are the way forward, you can customize Tetra Armour and sell for a huge profit.

Mostly the same as FREESHA's anwer but heres a link to Bingo's Top Tip - Easy Gil (cant be botherd writing out the tetra armour bit again lol)

http://tinyurl.com/5owjwx

Get Rikku's Godhand, then go to Omega Ruins, then just start looking for treasure chests in battle, steal from them, eventually a mimic will come out, kill it and you'll get 1000000 gil. And you get treasure chests and mimics pretty often.

Meant 100000 gil lol