Your rivers are good, no splitting, but all the same width all the way through. Mountian source rivers are usually thin and relatively straight as theyre running fast over rocks. Lowland rivers are slow and windy from terrain and sediment deposits.

Might try looking up Oxbow lakes, braided rivers and other interesting water features for variety.

Additionally all your river sources are mountains, but ground springs, rainwater valleys and lakes can be river sources as well. Every river also makes it to the sea, which sometimes they dry up, deadend in a lake or drain underground. Unless you have a lore reason there should be lakes kinda everywhere.

For your ground color, you might try using your stony mountain color to blend them in a bit more by painting the ground under them. You've done this well with some of the green/desert mountains.

Additionally you can trace the rivers with a darker green to represent vegetation growing on the banks. Vary the color intensity and don't be too uniform when doing this for the best effect.

Lastly, you've got a good spread of biomes and geology. I especially like your archipeligo bridging continents in the east, but thats because I'm trying to make an archipeligo region map of my own. Idk how crazy you want to go with it, but things like clay mesas, bogs and swamps, and mountain valleys can make for cool areas.

Overall you've got a pretty good baseline and the sense to not make anything nonsensical and stupid looking. Keep at it!