Breeding Hints are referred to as Breeding Tips in DragonVale World.
Breeding Hints can be found by opening up a dragon's profile through the "Dragon Menu" and viewing the requirements listed under the "Breeding Tips" heading.
Both standard and enchanted dragons require specific elements or dragon types to be bred. Enchanted dragons require the use of an Enchanted Crystal. Crystals can be crafted from shards in the breeding caves.