I'm only at the end of World 2 but...

World 1:

Fight Wild Dogs in the forest next to Karnak for 625 odd GP each!
Get a rod wielding job and fight the things in the desert south of Karnak (quadhapys?) and break an Ice Rod to win loads of EXP
Around Crescent Island fight 5 Black Flames in a group for a lot of GP/EXP
NEVER waste too many rods or skills on rendom battles, you'll find you're very lack, look at my example.

After desert:Fire Skill 50
Water Skill 23
Thunder Skill 50

Just be careful

World 2:

Use softs on teh Rock Statues iin Galuf's basement for 4-8 ABP

You already know, don't you?