In the waters north of Mirage Village (the one in the forest that is hidden) are giant birds called Giant Butterflies or Big Butterflies or somesuch. They give 8 AP and 5k g.

The key to gaining AP from them at a good clip is to kill them as quickly as possible. Some things I've found:

Make sure someone is always wielding the Assasin Dagger which will trigger instant death randomly.

When training up a Hunter have them equip the Monk skill !Store that stores energy and attacks the second round. On a critical hit you'll do around 7k damage.

Learning two swords and two handed is important when starting a character down the road of melee jobs. You can start a character down Knight until he gets 2-handed then switch him to another job like Samurai and let someone else work on knight.

Dual Wielding (2 swords) Double Lances comes out to 4 attacks for around 250 each. You won't typically miss more then one attack a round and most attacks connect for 245-258. Your character will do between 740-2000 damage.

Someone always needs to have the Caution ability. A back attack will zap your mana as you try to scramble to keep characters healed while squishing the enemy.

Berserkers are dead weight. Never have more then one on your team at a time. It is rare that they even get to attack before the enemy drops and when they do they miss a lot.

Buy everyone Winged Sandals/Shoes can't recall the exact name. They're sold in Mirage Village at the hidden armor merchant. He also has the rings of protection (Fire, Water, etc.) The Winged footware gives haste to the wearer.

For leveling up Monks, have them master another profession first, say Knight. Monk fists hardly do any damage, you're best bet is to use the ability to equip a Knight Sword or somesuch instead of fighting barehanded.

Have a designated healer. I use Reina because she's always been my support character. You can use different characters as the training requires. Even when you have it down to a science like I do things can still go wrong if too many people miss and the enemy doesn't go down as quickly as you expect.

If you're lucky the giant bird will appear with two giant sea creatures. In this case you gain 11AP for the battle and I think it is 13k g. On a related note, the Sword magic from the Sorceror job will kill the sea creatures in one hit. Cast Bolt3 on your weapon and it will eliminate them automatically upon attacking them. It really makes those rare battles easy.

You have a chance to steal a Katana from these giant birds called Monster Killer or Slayer or somesuch. If you find your Hunter isn't getting his stored attack off before the bird dies, change him over to !Mug.

Don't go so far North you hit a coastline or you'll end up fighting much weaker monsters. But a little south of that is where the birds are.

You best defense is a good offense. Your goal is to eliminate the birds before they can attack twice. You really hit your stride when you can eliminate them, without surprising them, before they can attack.

I'm probably forgetting things but that is all I can recall right now. If anyone knows a better way of earning AP by all means let us know the details.