ALWAYS use the same shades of colour for different geographical parts. For example: If Vallesia is mostly made of woods, then Upper Sehron should have the same shade of green too.
Mountains should be brown, and MOUNTAINS ONLY. ONLY the highest parts, the one which are covered with snow all year, have little white caps on them. White shouldn't prevail over brown. It doesn't matter where those mountains are(okay, except in Nordgard where every thing's covered in snow I guess), they should be brown.
Everything else which is not the desert should be GREEN. Thaigs, forests, grasslands, all GREEN. No exceptions there, except Nordgard and eternal snow.
Deserts are YELLOW with splotches of brown.
The transaction between different colours, except white, must be gradual. You can look here:[link]
1) Desert: It needs brown to balance out yellow and make it look, well, better. Also, deserts aren't flat in all parts. When you put any different geographical part(grassland, forest, ect.), you must put brown between them to create an illusion of gradual change between two areas.
2) Green parts: Besides everything being the same colour GREEN, there are subtle ways to make them different. FORESTS would have darker green spots with almost unnoticeable brownish tint in some parts. JUNGLES would have dark green as their main colour with hints of brown. Grasslands would have custom green with YELLOW, not brown, and 10% more noticeable.
3) PLACES ALWAYS IN ICE. Just put some brown between white and every other colour.
4) WATER. It has shades too. Lakes are almost white near the shore, but have light blue in the centre. It depends on how deep you want your lakes. The deeper the lake/sea, the darker the colour. Again, look for reference here:[link](I made this map, I know at least something of what I'm talking about)
The last but not the least: Text. It makes all the difference, I must tell you. Cities should be 100% opacity, while names of the regions, lakes, seas, should be at 50-60% of opacity. Choose one colour, font and a black outline for them all. The rest is all up to you.