The only thing that jumps out at me about the rivers is that the deltas look like they start really far inland. Most deltas will start splitting only about 30 miles from the shore. The Nile Delta begins about 70 miles inland, if I recall correctly.

Regarding getting your mountains and forests in the right place, put a layer mask each one and fill it entirely with black to hide everything. Then paint white on the mask with a soft brush where you want the features to appear. This will allow you to easily tweak the locations of your landforms later on by simply adjusting the mask. Black conceals, white reveals. And gray makes things translucent.