If you're going to play with colors, I would suggest you to try with few main colors, maybe one for each main area and then use ,for the smaller bonus zones, different shades of that color. Remember to test the result on vischeck to ensure your map is colorblind friendly.
Try to work also a bit on borders and rivers, now pixelous; take a look at that link, you can find some useful infos -->
viewtopic.php?f=466&t=98432#p2242704. The title is nice, but the arts on it get lost because is very small, try to make it more noticeable so it stands out a bit more.
There are some other things that could be commented, but since you have recently reached the graphics workshop, before going deeper with comments i'd like to see what you come up with your next update.
Nobodies

p.s. Not to waste your time, for now work only on one version, when you've your map almost ready for the forge you can produce the small (or the big) version without problems.