This is pretty much what I've been trying to do (check my gallery to decide for yourself how well I've accomplished it)
Some things you might want to look at are:
The Tweak tool
Stroke to Path
Fractalize and some of the other Extensions.
I never quite finished this tutorial, but it covers some of this stuff in a cursory way: http://www.cartographersguild.com/sh...Mapping-Basics