OK, for early levels
From 1 - 10 - Eastersand, Giza Plains....
From 10 -20 - Level up at Lhusu mines (don't go up the stair through the last stretch till you are at least level 13). Skeletons can be chained pretty neatly at the last straight stretch and they drop bone fragments like crazy which you can sell for 200 gil each, making a fortune
between 20-30, the best place to get gil and level up is the Simoon's Bluff at the Nam Yensa sandsea (teleport to Raythwall's tomb then go northeast). It is chock full of Bagoly (looks like an armored Ulstrix) that drop 1,000+ gil Bent Staff and of a blue turkey thingie that drops Rainbow Eggs that sell at around 550 gil. There's also a Wyvern that gives you some good Exp points. Try to chain the Bagoly - flee the turkeys and wyvern - to improve your odds of getting Bent Staff.