I had something of the same dilemma a while back: The Wheel of Time map

I used the official map as a guide to placing very rough and low-resolution contour lines. I am not really satisfied with it, but maybe looking at it might give you a place to start.

In terms of technique, I used the pencil tool to trace freehand over a scan of Mitchell's painting, but I do have a tablet, so that wasn't as difficult as it would have been had I been drawing with a mouse.