Start on some Scavenger missions (1+) any Chibi can do them and they yield good rewards and XP.

Once a Chibi has enough XP buy some skill points, that way it will be able to descent in the cave (3+) where first real loot awaits.

Chibis also don't like to travel alone, make sure to take Chibis along, more loot.

Start as early as possible The Hunt, animated Chibis and bloody battles await.