Final Fantasy X Tips

Early Money
The Al Bhed on the boat in the first section with Rikku will give you three potions. Dive into the water, swim on to the next screen, then come back and claim three more. Keep doing that until you have 94-99.

Sell all these potions when you reach Besaid, then on the boat to Kilika, keep kicking the suitcase in the hold. It will keep giving you potions until you have twenty in your inventory.