The map looks great so far. The color palette is fantastic!

The land lines around the continent are a little "generated" looking to which I sympathize. It appears you used the "expand selection" technique from Ascension (which is a fantastic look) but has some difficulty in making it look natural. I've had some luck with the "liquefy" filter and messing with the area to take away any straight lines and add a more natural look. I would suggest giving it a shot.

I also see you're giving my mountains a trial run. One thing to keep in mind is that you can erase parts of the mountains after you've placed them. For instance where your rivers start you could use a soft eraser to remove any overlapping mountains. This also works where you have the mountains placed very near each other just to clean up any overlap.

I would maybe try firmer borders between colors as well. Slimming them down to give them slightly more definition on the border itself and possibly feathering out the shadows of the borders a bit more.

I know it might be a lot of work, but I think a little more taper to the rivers from start to finish (just the big ones) might lend itself well. Also more defined river beginnings might aid in a more natural look. The current fade out works ok, but doesn’t look very natural by comparison with the rest of the map.

It's a fantastic start thought, keep up the good work!