Whichever it is, that's what I've been doing. But not only the geography but lots of other stuff such as government, religion, customs and trade. Plus so much more.
Thing is, for fantasy writers who create their own world, these are things you have to know.
So, for all who who create your own worlds, here's a really, really, really nice worldbuilding questionaire by Patricia C. Wrede.
Also, a Map Workshop from Holly Lisle.
Hope you enjoy. And I promise, I'll do better this month.