Hey man. First of all, good job so far.
If I'm not mistaken, you are following the Saderan tutorial, one of my personal favorites. I have one tip for you, which is to experiment with different brushes for the mountains. The ones you have now are pretty rough in my opinion, and perhaps a different brush would suit you better.

Good job on the new rivers, they feel alot more natural!
As far as the political borders, they are pretty good. I myself am not very fond of them and have a hard time coming up with ways to make them work.. So perhaps I'm not the guy to tell you anything regarding them. Still, if it counts for anything, they look pretty good.

Keep up the good work