The difficulty should be low, of course. And the speed should be fast. This is because it is an introduction, and one would wish the beginner to experience many things.
But the type of map, era, and the civilization, perhaps should depend to some degree on the person. For example, if your friend is a marine biologist, you may want a water theme for map and civ. A geologist, then get a land-dominant map, and let them pick the age of the planet. An Anglophile? Easy one. Warmonger? Perhaps raging barbarians. I'd just try to match the interests as much as possible.
And maybe how the teaching will be done is a factor: hot seat, or tutored, or multi-player? Not sure.