I've been developing a fairy tale esque world for my screenwriter friend. I decided to use our world as a bit of a framework in terms of developing a world from its creation. I knew I'd need to incorporate magic and such which led me to question how magic would work as well as its origins.
Being that it's a fairy tale world I decided to write a creation story involving a being who lived alone in a white void, forced into a state of self reflection. After some sort of revelation they willed a crown into being which tore the fabric of the white void and caused them to become a planet, then I decided to write the layers of the planet as layers of a human body as well with their heart becoming the core, the mantle being bones that can be moved as the world pleased (plate tectonics). And I decided that magical energy would actually be a layer between the mantle and the crust that represented the persons mind. This would infer a direct relation to the form of the planet so it had two continents, one in the shape of a crown, the other his skull. This would help me to create more info on how magic worked with different weight and density. Since magic represented the mind "heavier thoughts" would be negative and sink more towards the south pole leaving the lighter more positive thinking to raise to the north pole in a sorta oil and vinegar relationship. This would also mean along the equator there would be traces of both types to create a neutral energy.
Since creation and life are all branched from the existence of the being (and because a fair amount of fairy tales involve magic users intruding on the lives of royalty) I decided that evil magic users would live in caves in the forest because caves are closer to the arcane energy and therefore more accessible while being harder to find because of the trees. Humans being the crafty being they are would find ways to harvest and manipulate these energies into storage and such for use away from the sources, allowing for some magic on the go. This would also mean it's safest to hunt a witch who has left their lair since they have less magic to work with. I decided that the planet's mental growth would be shown by islands forming along the neutral energy or rather, separating them from the crown. From there I intend to develop the kingdom in the north in terms of its political landscape, and their views on things such as foreign policy and what differences of views would be seen by what villages. Once that and the land to the South is developed I'd be deciding on artifacts of power. Afterwards I would intend to develop the zoology with things like dangerous beasts, mysterious creatures (after all, with natural magical energies, creatures and nature would create some interesting variations) and even domesticated animals for things such as transportation, food, and pets. Basically I split my development of a world into it's first planet as such
1. The World Itself
2. The People of the World (Including culture, religion, and politics)
3. Zoology
4. Magic Stuff
5. Artifacts of Power