Have any tips?

Well for stat maxing I got a pretty basic set up. Buy 100 tents, turn them into mega potions with Recov Med-RF four times. Sell the mega potions. Doing this a few times will give you some extra gil. 450,000. Keep doing this until you have a lot and I mean a lot. Go to esthar Pet Shop and buy (depending on what stat you want to start maxing) Giant's ring (HP), Power Wrist (Strength), Force armlet (Spirit), or Hypno Crown (magic). Buy a 100 of which ever then turn them into the next level of items with GFAbl Med-RF. You should have 10 good items now. Note that these items are the best stat bomus' you can teach your GF. Once you did that go to Forbidden Med-RF. Finally get your "up" items. Rinse repeat.

Next is Devour. Which takes a little patience cause the enemies that bring your stats up are semi rare. Red Dragon (HP) T-rex (Strength) Adamantoise (vit) Behemoth (magic) and Marlboro (spirit).

The only one that is hard to buy can be done in an easy way. That stat Vitality. To buy you need, Vit Scrolls (500 for one vit up) then turn the vit scrolls into a few orihalcon with GFAbl Med-RF then with the same skills turn orihalcon into Adamantine. Then you need 5 adamantine to equal a vit up. That way is BS really. Instead head to Dollet - Long Horn Island. On the beach you can face Adamantoise which will drop the adamantine and also you can devour them to raise Vit. beats spending like 3000000 Gil on Vit scrolls.

So do you have any useful tips on making characters better?