Great work on continuing to improve your map, keep it up. As you can see below, this was my first draft of Tribal War - Florida, and extremely far from what the site requires, and deserves.
Tribal War - Florida v1.0
- Click image to enlarge.

Eighteen months later and the map was finally quenched. Here's a couple of things, and feel free to use whatever works for you.
Borders: There's not much you can do except go back over with the path tool, which will make the outlines nice and smooth. If you don't like that, you can always jag it up in other ways, still using the paths you've created. I'm sure some others have a better way to do that, but my way would be to just add more points along the path, and then use the squared edge setting when stroking them. I use a 2px stroke, so much tighter than what you have currently.
For the main map, the way I would do it is, to basically start with a path for each large area, Then the smaller areas, etc. This will allow you to easily fill each area in with color or texture by using the Path to Selection, then just drop your color in, making sure to use a different layer for each one. Then I go back in and create a path around each individual tert or a line, etc. to create the lines/borders for each tert. This will allow you to easily move them around as needed later on, which will invariably happen. This is not fun, but just put on some Floyd, zone in and I'm sure you can knock it out in a couple of days.
Also, as asked prior, what time period are you looking to set the map in, that will determine the type of theme you go with, etc.. Also, think about all of the explanatory text to set the tone for the map. Personally I'm a quote man, you'll see one on every map I do. "There is no death, only a change of worlds", Chief Seattle. "All these are the twelve tribes of Israel", the Old Testament. "Do the unexpected, attack the unprepared", Zhuge Liang. "Not all those who wander are lost", Tolkien.
Don't forget you'll need room for a legend, or mini-map, as well explanatory information, etc.
Keep up the nice work, but you have a long way to go. You might also want to save up some of the map update posts until you get a little more meat on the bone, if you know what I mean, unless you are looking for feedback on a perticular direction, etc.
Either way let me know if you have any questions, and don't give up!!