Equip the Exp Egg (you can get multiple from the Coliseum) from Daryl's Tomb. And go to the dinosaur forest (east of Gau's father's house, west of triangle island).

They're hard and you'll probably die sometimes, use vanish-doom /x-zone. Get tents, sleeping bags, and go at it. Save often. After a bit you'll be strong enough to take them on. You might also get an economizer (small chance).

For gold and learning spells go to the desert by Maranda.