You learn a thing or two when you start looking. That's about as much as I know.

If you want someone to include countries with border lines, you'll need to provide a much larger sketch with a rough layout of their names and placement on the continent. And if they're dependent on specific natural features like mountain ranges, rivers, forests, etc, then you'll want to include some sort of guideline of description for them... drawn and/or written. You've already written a large portion of your book, yes? And you have ideas drifting through your imagination about the larger world, and types of people living in different parts of it, yes? So as many details as you can give up front would be helpful, in order that it ends up looking like what you have in mind. Unless you want to be as surprised as your character will be when he walks off the edge of a very large cliff that wasn't there yesterday. =)