This looks pretty darn good so far and kudos on some great river systems. I might put a dark blue color over the deep ocean so that the white lines don't show there...they're pretty dominating. The north looks very vivid with that light yellow-green...I might go for something more light grayish brownish green. Your icy mtns might also need more white instead of brown...I'd put a layer of white on top of them and set the blend mode to color or hue and then erase like drawing a crack (this leaves plenty of white but gives a tiny hint here n there of brown). Lastly, it looks very bumpy...I'd take out a big eraser and turn the opacity down to 10% and erase a bunch of bumps...or use a blur tool on them to soften them. You've got a great basis here and you certainly understand the techniques and where you want to go with them. My suggestions are more aesthetic so you can take em or leave em It's pretty nice nonetheless.