I drew the contour lines drawing freehand in an image editor. I've since done the coastline and rivers in Wonderdraft. I'm still deciding how to continue the map, whether freehand or in WD. I have made a few issues/decisions for myself though! As I say, an experiment that I'm learning from.. Images showing what I have so far (they have transparent backgrounds).
UntitledColoursContours.png
UntitledContoursandLakes.png