This is a solid first piece, Soulcreek! You should be proud.

To just jump on what everyone else is talking about... I recommend matching the thickness of the border with the width of the strokes used in the landforms/flora Looks like it's about 3px on average and your edge is about double that. It'll make it look like everything was drawn with the same pen.

Also, consider outlining some of those wider rivers and then tapering them to solid as they narrow/grow younger, it'll bring more of the blue into the map.