TheCatholicCrow
Inkling
When beginning a new fantasy novel, I ask "Who are the main characters, and what culture do they come from?" I trained as an anthropologist, and to me, culture determines characters' world views and beliefs. Once you determine the culture, many of the character details will fill in automatically. Then, as I fill in an outline of those details, I work out the back story: relevant personal history, relevant cultural history, the physical setting, the magic systems (religious and secular, male magic and female magic), etc.
^^^ THIS! ^^^
Anyone with an Anthro background will probably agree ... but yeah ... establishing culture is HUGE.