Well I can say that I like the effort you have taken to make the rivers. Even though they seem out of proportion(width) they look awesome. The tree brush looks nice but I'm not a fan of the forest filling you did. Also the mountains seem too uniform. As for the color I think it is generally ok, maybe a bit darker mountains/forests and I would add a layer of very light grey/blue color around the coastline to symbolize the water (there is I think a short picture tutorial by -Max- in his workshop thread that uses that style of water layer around the coastline). About the borders..uff..I also had/have a trouble finding out something good. Probably since it differs a lot from map to map. I would try making a pattern in some LOTR style and then make a rectangle path around to use as a border. But as I said borders are also my weak point so take this with a grain of salt.
Cheers,
Barek