Basically, make the best bad you can. Break all the 'rules', with river violations galore, climatic impossibility, inconsistent scales and people who wear hats on their feet. Rivers can flow upstream (without any of that silly tidal boare nonsense), rain shadows occuring on the winward sides of mountains... Just make it all so terribly wrong, and the wronger it is, the better the outcome! Turn all the conventions and rules on their heads, and make the best awful map ever!

>evil chuckle<

Let me know what you reckon!