Welcome to the Guild HDJones! I'm a big fan of GIMP myself. However the latest version has problems with Wacom's tablets, so you are actually better off just working with a mouse. It's slow going, but it can be done (I should know, I've done it). There are plenty of great tutorials here for GIMP, as well as a few great tutorials on hand drawn style maps. I'd spend a good solid few hours in the tutorials section familiarizing yourself with what's out there and then plunge into a tutorial or three. Let us know if you have any questions about anything.