Hannah - I like the sky and the reflections in the water, but, in MHO, there seems to be a disconnect between the two. Thad

quite good

Very atmospheric. Good work.

This is beautiful...It would look great in a video...

OK I am going to try and give some advice... keep in mind I haven't used TG for a few years so I won't be able to remember specific commands but I will try to make it as clear as possible.

I think this is the best of your TG renders uploaded so far, and probably the most realistic (which is what you should be aiming for, even in "alien" environments you should still try to make it look as believable as possible). There are a few things that detract from that realism; firstly the curvature on the horizon, which I think you can fix by altering the size of the "planet" you are working with... as I mentioned before I can't recall where this function is or exactly what it is called but I am pretty sure there is an option somewhere which allows you to specify the size of the globe, obviously the larger it is the less curvature is visible. There might also be some camera setting which causes the curving effect.

I would reduce the visibility level in the water or increase the reflection level so that the terrain was not visible at the bottom of the lake. You can also use the terrain settings to create a different texture when you get to the water level however this is more complex and I probably wouldn't worry about it until later...

I think the terrain could be more interesting, the mountains feel a bit "detached" from the scene and the terrain in the foreground appears flat and uninteresting. Personally I find the best solution to this is to move the camera around until you find a good landscape, rather than trying to manually create one.

The sky is the most appealing part of the image IMO; it probably doesn't need to be changed but you could try altering the height of the sun to try to get some interesting shadows or regenerating the cloud so that you get it more off to the sides (think of the rule of thirds). The way I usually work with TG is to work on a single aspect, such as terrain, until I am happy with it, then move on to water bodies, then clouds, then sunlight, then sky color, then terrain texture etc. The most important thing to remember when working this way is to save continuously, and save under a new file name every time you make a major change as it is usually almost impossible to make things look the way they were again once you change them.

If you have any questions I would be happy to TRY and answer them for you... maybe I'll even dust off TG this weekend and reacquaint myself...