"Sun" (or whatever star there is at the heart of the planet system) is assumed to be so far away from planets that it is at an "infinite" distance. So the lighting on both moon and planet should be very close. Here, the right side of the moon is enlighten, and the left part of the planet is too, that would mean the sun is between both of them... and also mean the sun is very close. Here, there is no viewable sun between the moon & the planet... So the lighting of planet/moon is abnormal (and the lighting on the place the dragon is looks dark, assuming it's the dark side of the planet/moon... So the lighting on the moon/planet the dragon is stood on is also strange O.o)
The size of the planet leads me to think that the dragon is standing on some kind of moon (moon can have some grass, alright, I have no problem about that). Was it meant to be? Or was the dragon supposed to stand on a normal planet? In this second cas, the moon is way too small (or the ringed planet is way too big) for the dragon's planet to be (the ringed planet should attract the dragon's planet and both should have merged a long time ago)... Yes, there are still possibilities for such planet-configuration to exist, but that's very... strange hmm Maybe I should just stop thinking xdd
Dragon's great, his (her? I don't remember ) lighting body parts contrast with the dark behind, and respond to the moon's light & stars, so that's a contrasting thing but it's still well added to the picture So does the red body with the blue background
Oh, almost forgot... If planet's rings are not glowing (aka it doesn't emit light), then you can shadow them: the planet should project its shadow on the rings behind. If rings emit some light, you may have a small ("light") shadow on those rings, behind the planet. Rings are made of small matter with a fast orbit around the planet; you can use a rotation-motion blur on the rings to give a bit more dynamism on the rings and on the picture.