RPG World WIP

[Hafnium]

I decided to start coming up with some graphics for a RPG campaign setting I've been working on. Here is my basic textured world map. I'll be posting updates over the next few week and any critiques would be greatly appreciated.

I do have a few questions for you experienced cartographers.

1) What is the best way to draw rivers in this style of map? I tried cutting away from my land mask but this is tedious and looks kinda ugly. I want the rivers to extend up the mountains a bit as they would in reality.

2) My Ice - Land transitions look pretty ugly. What could I do to fix this?

3) What could I do to the desert regions to make them more desert - y...?

EDIT: 4) Wow, my arctic coast looks horrible in the thumbnail.

I will continue to work on this project. Once again, feedback is greatly appreciated.

EDIT: I just noticed the little sircle in the center of the ocean. I have no clue how it got there. It was hiding in the ocean's color layer... I'm not going to bother reposting it for that one small fix.