To avoid the bevel look, don't use 'em. Sure, we know there is a groove cut into the land by the river but in reality that groove is so shallow so as to be nil (except in mountains or canyons). Instead, paint some darker greens around the river to represent the fertile river valley. Don't use outer glows, they look fake and go into the ocean which requires a bunch more steps to get rid of.

The mountains around the desert look like a fence keeping the sand in...thus kinda fake. Chop some out so it looks more natural and flowing. Otherwise, looks pretty good.