Easy AP and experience in Chapter 1
Note: This trick requires a controller with an auto-fire feature. At the start of the game after the fight with "Yuna" and during the chase, you will fight two goons. In the next area, you will fight two goons and two fem goons. In that roomm run over to the dock and you will see a Mog bent over and shivering. When you try to talk to it, it will heal you fully. Set yourself directly against her, and use the auto-fire feature. A fem goon will run around the corner and attack you. Remain there for a few hours to get all of ability for the thief and warrior.
Easy money in Chapter 2
Clear off O'aka's debts by buying 100,000 gil worth of items from him on the Airship. After you have cleared the debt, O'aka will start selling you items very cheap. Buy 99 of the items he sells, then fly to another location and sell them at over twice what you bought them for. For example, buy 99 High Potions from him for 50 gil each (total cost of 4950 gil). Then, fly to the Calm Lands and sell the High Potions for 125 gil each, for a total of 12375 gil. That is a quick profit of 7425 gil.
Instead of traveling to another place after you pay off O'aka's debt to make a profit of a little over 7,000 gil, just buy 99 Hi-potions from O'aka for 50 gil apiece. Then, go over to the Barkeep (behind the counter on the Airship in Cabin, which is next to where O'aka is selling) and sell him the Hi-potions for 125 gil each. This makes it easier to make money much faster rather than to travel to another shop to keep selling Hi-Potions.
Note: Once O'aka's debt is paid and you have enough money, buy 99 of everything from him, then sell all of that to the barkeep. You will make a profit of 16,830 gil.
To do this, you must be within Chapter 2 and talk to Tobil. He is at the MoonFlow. During Chapter 1, you must save the delivery trailer from the bandits, and upon doing so, Tobil will give you a Dress Sphere. Within Chapter 2, talk to Tobil yet again. He complains that no one is buying tickets and puts you up to the job in doing so. You can also make a huge profit. Use this to make 10,000 gil within five minutes. You only have ten tickets. The customers are as follows:
Al Bhed Woman wearing pink near entrance (will pay 1,500 gil)
Woman wearing red headband, before reaching Tobli (will pay 1,500 gil)
Woman standing beside child, after Tobli (will pay 1,000 gi!)
Woman wearing yellow and orange, standing across from Save Sphere (will pay 1,500 gil)
Man wearing orange and green, sitting on bench (will pay up to 1,000 gil)
Person wearing green, sitting on dock stairs (will pay 1,500 gil)
Person wearing green, standing next to dock (will pay the highest price)
Go on the other side of the Moonflow (ride the Showpuff); the child wearing white shirt, standing beside Hypello (will pay up to 2,000 gil)
Person in yellow dress standing at the top of the ramp, same side of the Moonflow as the kid above (will pay 2,000 gil)
Woman in green standing across from the bench in the direction of going to Guadosalam (will pay any amount of gil)
Your reward should be 10,000 gil or higher. You also will receive Seething Cauldron Garment Grid, Muscle Belt.
During Chapter 2, visit Guadosalam. Visit the hotel owner and choose the "Got any data?" option. Note: Save the game first. The hotel owner will ask for 10,000 gil for a clue regarding somebody in Guadosalam who could buy the data from you. Pay the person. If the clue is "It's the last person you'd expect, no question", the buyer for some reason is the person who you bought the data from. If it is a different clue, restart the game and keep trying until you receive that clue. If you get the clue, return to the hotel and press Square to ask if the hotel owner wants to buy the data. He says "Yes", and in return gives you 100,000 gil, giving your an easy 90,000 gil profit.
Easy AP in Chapter 2
Be on Chapter 2 with a Lure Ring, White Mage Dressphere, and the dresses you would like to master. Go to Besaid Islands and to the zone where there are the waterfalls and bridges. When heading frp, the Save Sphere towards the beach, you will reach the first of the two bridges. Behind the first one is a little passage to go down. Down there is a chest containing an item (varies depending on the chapter). Once there, set up one of your three characters as a White Mage and the other two as characters where the first command is to attack. Note: This does not work for Black Mages. Once you have the proper dress on, equip one with the Lure Ring. If you have time, leave the menu screen, and hold Left. A battle should happen quickly, and the enemies (if done before the end of the chapter) should be easy to defeat. Hold X and the two fighting classes will instantly attack, and the person as the White Mage will do Prayer, healing them back to full health. To do this automatically, tape the Analog-stick to the left, causing the character to run left. Since nothing needs to be pressed Left in battle screens, it will not effect the battle. Also, tape down X. Watch a few battles to make sure it is working correctly. In a little over an hour, you can master one Dress Sphere per person. Note: Change the dresses, keeping at least one a White Mage for an easy AP gain.
Easy experience in Chapter 2
When you have completed the first level of Gunner's Gauntlet on Chapter 2, (defeating the man with 500 points on Besaid Island), play it until you complete level 6 by obtaining 1300 points. After that, try the next level. However, instead of trying to obtain the minimum (1,400 points), try for 2800 points. With some practice, and if you are able to keep your chain bar full, it is an easy shot. If you do not reach 2800 points, do not finish the game. Instead, die or let the timer finish. Getting 2,800 points on max level is more difficult; there are too many enemies and you do not have time to kill them all without being hit. Also, on level 7 there are a lot of enemies, but just enough to give you time to kill them. Another trick to avoid being hit is to go behind the last big waterfall in the area just before the big machina, and stick to the ledge closest to the screen. This way, monsters will pass behind you without hitting you; the only thing you have to worry about is having enough ammunition.
Easy experience in Chapter 3
After you save the tourists in Chapter 3, go back into the Cave of the Stolen Fayth and equip a Lure Bracer on one of your characters. Battle here for a few hours for easy experience and AP. This is also a good location in Chapter 5 as well, but not as good as in the Farplane. After you defeat Shiva, spend some time running around the Save Sphere that she leaves behind. This is the best place to train in the entire game.
Easy AP in Chapter 5
Be on Chapter 5 with a Lure Ring, White Mage Dressphere, and the dresses you would like to master. Go to Bevelle and to the underground passage that the Kinder Guardians found. After talking to the old man, and getting Crimson Sphere 6, run straight and drop down the hole. You will be on level one. Make sure the level is like a circle, with a Ton Berry standing on a small platform by himself when you first enter. If it is not set up like this, restart the level repeatedly until it is. Once it is like that, go to the top left corner. Once there, set up one of your three characters as a White Mage and the other two as characters where the first command is to attack. Note: This does not work for Black Mages. Once you have the proper dress on, equip one with the Lure Ring. If you have time, leave the menu screen, and hold Left. A battle should happen quickly, and the enemies should be easy to defeat. Hold X and the two fighting classes will instantly attack, and the person as the White Mage will do Prayer, healing them back to full health. To do this automatically, tape the Analog-stick to the left, causing the character to run left. Since nothing needs to be pressed Left in battle screens, it will not effect the battle. Also, tape down X. Watch a few battles to make sure it is working correctly. In a little over an hour, you can master one Dress Sphere per person. Note: Change the dresses, keeping at least one a White Mage for an easy AP gain.
Black Lore in Besaid
In Chapter 3 and 4m go into the village of Besaid and run against the dog that is running around there. This is the same dog that gave you Valefor's secret bonus Overdrive in Final Fantasy 10. If you run at him and press X enough, he will cough up the Black Lore, which is an accessory that allows you to use your Black Magic.
Rikku's Special Dressphere in Bikanel Desert
Go to Bikanel Desert during chapter 2. Nhadala thinks something that strange is happening near the Oasis. Talk to the pilot twice and ask him to go to the Oasis. When you arrive, go to the waters edge and you will get Rikku's Special Dressphere Machina Maw. Note: You can only get the sphere in chapter 2.
Besaid Key in Calm Lands
In Chapter 3 when you have to fight all the Aeons, go to the Calm Lands cave where you obtained Yojimbo. You will be assigned to a mission. Complete it, and the man that you rescue in the mission will give you the Besaid Key.