Is this 2D or 3D?
Regardless of the technique I would try the following things, but execution might vary depending on the technique.
1) reduce cloud altitude
* looks like you are using a cloud sphere above ground sphere, and a dark version of the clouds as the shadow the same size as the ground. If you make the cloud layer closer to the size of
2) reduce cloud shadow darkness
* it's quite dark, almost black right now. I suggest using the dark cloud layer in Multiply mode if it is in 2D, and reducing its opacity
3) break up the uniformity of the "high clouds".
*currently, the clouds that are casting shadows seem quite uniform white, and have very sharp edges. This is sort of hard to address, but I would suggest careful application of blur and smudge brushes, or something. The problem with these uniform white blobs is that they look more like glaciers floating in air, than clouds.
3) make water a darker blue and reduce sun glare gradient size on water
* water is a rather dark blue colour except where sunlight is directly reflected, and the specular reflection size is quite small.
4) reduce thickness of the atmosphere around the planetary edge, but make it reach "in" over the planet a bit more.
* atmospheric effect is what makes earth-like planets blue. It tends to add a a slightly bluish tint to areas toward the "horizon" (the edge of the visible area).
* the atmospheric glow should reach up to like 100-150 km maybe. It is much thinner band around the planet than people usually start with.
* this is usually because people use ubiquitous
Low Earth Orbit photography as the "model" of what they wish to achieve; at low altitude, the atmo glow is quite prevalent and thick, but as you move away further into space, it gets progressively thinner (and hard to balance in 2D art; 3D model is usually easier to do by virtue of having the scale of the atmosphere built-in (though it depends on the technique you make it with)
5. add variety to terrain colouration
* currently seems like mix of greens and drab brown/tan colours
* try adding some different greens for different types of vegetation. Northern forests are usually less saturated green than the lush rainforests on the equator.
* also different sort of deserts (Sahara for example looks like mixes of yellow and reddish or slightly orange sand)
* mountain ranges (greyish brown) with snow covered tops and green valleys
6. Reduce the bump mapping slightly
* in high orbit shots, everything except largest elevation variations (mountain ranges) typically look rather flat. It's easy to be overzealous with height mapping the planet.
7. increase resolution of base textures
* this is always a good idea IMHO - go as high as you comfortably can. What sort of textures are you using anyway? How are you making them?
Note that these are representative of what
I think a planet should look like. Don't go out of your way to make the planet look like something you don't want it to look like. That said, the listed things are something you might want to experiment with to find what they do to the overall
