Big Update for the win~~
Now I am at the exact point I was in my former file: just before Cleyra.
Gizamaluke's Grotto: Easy, AGAIN. Two tries for each pair of Black Mages.
Burmecia: Even easier, AGAIN. First try at the Black Mages AND to revive Quina with 1 HP.
Treno: Here, I bought the Reflect Ring as soon as I could, I also bought two Magician Robes to Vivi and Quina, the Madain's Ring (It can make battles against Alexandria Soldiers easier) and some other items. I leveled Marcus up to Lv25 again (and this time I got lucky with Ethers, I have 26 XD), and I have EXACTLY 100k gil. (Really, it's funny to see "100000 Gil" in the menu XD)
EDIT:
Cotton Robe Trick >>
Buy 99 Wrists at Dali - sell Ethers and Phoenix Pinios to get enough money. Always have one of each, though.
Whn you get at Lindblum, purchase one Steepled Hat (may can steal one of Blçack Waltz 2, and another one from Black Waltz 3), be sure you have 1000 Gil, and synth one Cotton Robe. Sell the Cotton Robe, but another Steepled Hat, make Cotton Robe, sell the robe. Rinse and repeat. As you get more money, buy more Steepled Hats. You should have 60~65k Gil when you synth ALL the Wrists. BE SURE TO LEAVE AT LEAST ONE COTTON ROBE IN YOUR INVENTORY, to give to Quina or Vivi (it depends on who is using the Bronze Vest). After that, buy 99 Steepled Hats.
On Disc 2, after Black Waltz 3 fight, go to Dali, buy 99 Wrsist (and two or three Rods to make Coral Rings XD). Go back to Treno, and do the trick again. You should have 100~105k Gil after that, more than enough until Disc 2's end.
You can do the trick AGAIN (buy 99 Wrists at Dali again, and when you go back to Zidane, buy 99 Steepled Hats from Atla's Mogshop, and synth them in Lindblum, after Ramuh's event). But it is totally optional. 100k is more than enough.
EDIT 2:
Updates~
Cleyra was intense. But I was lucky enough to do everything in my second try (in the first try, Xidane criticalled the Alexandria Soldier in the first battle xD). Now I am preparing for the second hardest part of the game... x.x