Hi Plague, good start.
As you ask for advice:
I like the red version better than the green, although it doesn´t look as earthlike realistic, more alien.
Variation in the colours is one thing, you can achieve that in different ways. You could use child layers for example, just attach one or more surface layers to th child-layer input of your green grass layer, give them low coverage, restrict by altitude and/or slope and give them slightly different shades of green or brown. Childlayers appear only where their "mother" appears, but not necessarily everywhere it does.
Learning how to use plant objects would of course add another level to the image. You could start by "Objects->add population-> grass clump. You can use your green layer as a mask to restrict where the objects appear.
Maybe you could lower the point of view then to have a foreground, that would also be an improvement in my opinion.
Cheers,
J