Ok, how about a point-by-point?
Assuming that I'm trying to replicate 12th century europe in 'broad strokes'...
1. The 'dominant' religion is a very low-key 'do-unto-others' sort of church, and it has a small (four-member) pantheon, is divided into many different sects and factions (and therefore lacks centralized power of any kind), and ultimately plays only a minimal role in Big Stuff when compared with economic and political power-centers (kings, trade guilds, etc.). As such, they don't really have the power or gumption to persecute other religions.
2. There are mythic creatures, including but not limited to fairies, a dragon or two, spirits that embody various different things (as well as the spirits of the dead), animated corpses, extra-big animals and insects, and various sorts of giants, all of which live in their own parts of the wilderness.
3. There are humanoid beings other than humans, including elves (the calm, reserved survivors of a once-great civilization, who have retreated to the forest), dwarves (great craftsmen, reduced to a mere fraction of their former numbers, and forced to live among humans), orcs/goblins/trolls (the progeny of an evil god in the distant past), and gnomes (curious forest-dwellers; the most civilized of the fey).
4. Varying degrees of gender equality (at worst, women can take most vocations, but some are frowned upon, and at best, there aren't any distinctions).
5. A very, very, very, very, very, very small percentage of the human population can use magic--however, they cloister themselves in isolated places, and, as such, most people don't believe they're "real". Generally speaking, magic is rare enough that most people won't see magic even once in their entire lifetime.
Those are the major ones. By and large, the sociocultural system is within the range that europe and similar agrarian regions have existed within (monarchs at the top, farmers at the bottom).
That said, I don't have most of the lame, setting-breaking D&Disms that a lot of people fail to account for because...well, I don't run the setting with D&D; Grim Tales is just a better system for it. And besides, it's more fun this way.